1// -*- C++ -*-
2//===-------------------------- algorithm ---------------------------------===//
3//
4// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
5// See https://llvm.org/LICENSE.txt for license information.
6// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
7//
8//===----------------------------------------------------------------------===//
9
10#ifndef _LIBCPP_ALGORITHM
11#define _LIBCPP_ALGORITHM
12
13/*
14    algorithm synopsis
15
16#include <initializer_list>
17
18namespace std
19{
20
21template <class InputIterator, class Predicate>
22    constexpr bool     // constexpr in C++20
23    all_of(InputIterator first, InputIterator last, Predicate pred);
24
25template <class InputIterator, class Predicate>
26    constexpr bool     // constexpr in C++20
27    any_of(InputIterator first, InputIterator last, Predicate pred);
28
29template <class InputIterator, class Predicate>
30    constexpr bool     // constexpr in C++20
31    none_of(InputIterator first, InputIterator last, Predicate pred);
32
33template <class InputIterator, class Function>
34    constexpr Function          // constexpr in C++20
35    for_each(InputIterator first, InputIterator last, Function f);
36
37template<class InputIterator, class Size, class Function>
38    constexpr InputIterator     // constexpr in C++20
39    for_each_n(InputIterator first, Size n, Function f); // C++17
40
41template <class InputIterator, class T>
42    constexpr InputIterator     // constexpr in C++20
43    find(InputIterator first, InputIterator last, const T& value);
44
45template <class InputIterator, class Predicate>
46    constexpr InputIterator     // constexpr in C++20
47    find_if(InputIterator first, InputIterator last, Predicate pred);
48
49template<class InputIterator, class Predicate>
50    InputIterator               // constexpr in C++20
51    find_if_not(InputIterator first, InputIterator last, Predicate pred);
52
53template <class ForwardIterator1, class ForwardIterator2>
54    ForwardIterator1            // constexpr in C++20
55    find_end(ForwardIterator1 first1, ForwardIterator1 last1,
56             ForwardIterator2 first2, ForwardIterator2 last2);
57
58template <class ForwardIterator1, class ForwardIterator2, class BinaryPredicate>
59    ForwardIterator1            // constexpr in C++20
60    find_end(ForwardIterator1 first1, ForwardIterator1 last1,
61             ForwardIterator2 first2, ForwardIterator2 last2, BinaryPredicate pred);
62
63template <class ForwardIterator1, class ForwardIterator2>
64    constexpr ForwardIterator1  // constexpr in C++20
65    find_first_of(ForwardIterator1 first1, ForwardIterator1 last1,
66                  ForwardIterator2 first2, ForwardIterator2 last2);
67
68template <class ForwardIterator1, class ForwardIterator2, class BinaryPredicate>
69    constexpr ForwardIterator1  // constexpr in C++20
70    find_first_of(ForwardIterator1 first1, ForwardIterator1 last1,
71                  ForwardIterator2 first2, ForwardIterator2 last2, BinaryPredicate pred);
72
73template <class ForwardIterator>
74    constexpr ForwardIterator   // constexpr in C++20
75    adjacent_find(ForwardIterator first, ForwardIterator last);
76
77template <class ForwardIterator, class BinaryPredicate>
78    constexpr ForwardIterator   // constexpr in C++20
79    adjacent_find(ForwardIterator first, ForwardIterator last, BinaryPredicate pred);
80
81template <class InputIterator, class T>
82    constexpr typename iterator_traits<InputIterator>::difference_type  // constexpr in C++20
83    count(InputIterator first, InputIterator last, const T& value);
84
85template <class InputIterator, class Predicate>
86    constexpr typename iterator_traits<InputIterator>::difference_type // constexpr in C++20
87    count_if(InputIterator first, InputIterator last, Predicate pred);
88
89template <class InputIterator1, class InputIterator2>
90    constexpr pair<InputIterator1, InputIterator2>   // constexpr in C++20
91    mismatch(InputIterator1 first1, InputIterator1 last1, InputIterator2 first2);
92
93template <class InputIterator1, class InputIterator2>
94    constexpr pair<InputIterator1, InputIterator2>   // constexpr in C++20
95    mismatch(InputIterator1 first1, InputIterator1 last1,
96             InputIterator2 first2, InputIterator2 last2); // **C++14**
97
98template <class InputIterator1, class InputIterator2, class BinaryPredicate>
99    constexpr pair<InputIterator1, InputIterator2>   // constexpr in C++20
100    mismatch(InputIterator1 first1, InputIterator1 last1,
101             InputIterator2 first2, BinaryPredicate pred);
102
103template <class InputIterator1, class InputIterator2, class BinaryPredicate>
104    constexpr pair<InputIterator1, InputIterator2>   // constexpr in C++20
105    mismatch(InputIterator1 first1, InputIterator1 last1,
106             InputIterator2 first2, InputIterator2 last2,
107             BinaryPredicate pred); // **C++14**
108
109template <class InputIterator1, class InputIterator2>
110    constexpr bool      // constexpr in C++20
111    equal(InputIterator1 first1, InputIterator1 last1, InputIterator2 first2);
112
113template <class InputIterator1, class InputIterator2>
114    constexpr bool      // constexpr in C++20
115    equal(InputIterator1 first1, InputIterator1 last1,
116          InputIterator2 first2, InputIterator2 last2); // **C++14**
117
118template <class InputIterator1, class InputIterator2, class BinaryPredicate>
119    constexpr bool      // constexpr in C++20
120    equal(InputIterator1 first1, InputIterator1 last1,
121          InputIterator2 first2, BinaryPredicate pred);
122
123template <class InputIterator1, class InputIterator2, class BinaryPredicate>
124    constexpr bool      // constexpr in C++20
125    equal(InputIterator1 first1, InputIterator1 last1,
126          InputIterator2 first2, InputIterator2 last2,
127          BinaryPredicate pred); // **C++14**
128
129template<class ForwardIterator1, class ForwardIterator2>
130    constexpr bool      // constexpr in C++20
131    is_permutation(ForwardIterator1 first1, ForwardIterator1 last1,
132                   ForwardIterator2 first2);
133
134template<class ForwardIterator1, class ForwardIterator2>
135    constexpr bool      // constexpr in C++20
136    is_permutation(ForwardIterator1 first1, ForwardIterator1 last1,
137                   ForwardIterator2 first2, ForwardIterator2 last2); // **C++14**
138
139template<class ForwardIterator1, class ForwardIterator2, class BinaryPredicate>
140    constexpr bool      // constexpr in C++20
141    is_permutation(ForwardIterator1 first1, ForwardIterator1 last1,
142                   ForwardIterator2 first2, BinaryPredicate pred);
143
144template<class ForwardIterator1, class ForwardIterator2, class BinaryPredicate>
145    constexpr bool      // constexpr in C++20
146    is_permutation(ForwardIterator1 first1, ForwardIterator1 last1,
147                   ForwardIterator2 first2, ForwardIterator2 last2,
148                   BinaryPredicate pred);  // **C++14**
149
150template <class ForwardIterator1, class ForwardIterator2>
151    constexpr ForwardIterator1      // constexpr in C++20
152    search(ForwardIterator1 first1, ForwardIterator1 last1,
153           ForwardIterator2 first2, ForwardIterator2 last2);
154
155template <class ForwardIterator1, class ForwardIterator2, class BinaryPredicate>
156    constexpr ForwardIterator1      // constexpr in C++20
157    search(ForwardIterator1 first1, ForwardIterator1 last1,
158           ForwardIterator2 first2, ForwardIterator2 last2, BinaryPredicate pred);
159
160template <class ForwardIterator, class Size, class T>
161    constexpr ForwardIterator       // constexpr in C++20
162    search_n(ForwardIterator first, ForwardIterator last, Size count, const T& value);
163
164template <class ForwardIterator, class Size, class T, class BinaryPredicate>
165    constexpr ForwardIterator       // constexpr in C++20
166    search_n(ForwardIterator first, ForwardIterator last,
167             Size count, const T& value, BinaryPredicate pred);
168
169template <class InputIterator, class OutputIterator>
170    OutputIterator
171    copy(InputIterator first, InputIterator last, OutputIterator result);
172
173template<class InputIterator, class OutputIterator, class Predicate>
174    OutputIterator
175    copy_if(InputIterator first, InputIterator last,
176            OutputIterator result, Predicate pred);
177
178template<class InputIterator, class Size, class OutputIterator>
179    OutputIterator
180    copy_n(InputIterator first, Size n, OutputIterator result);
181
182template <class BidirectionalIterator1, class BidirectionalIterator2>
183    BidirectionalIterator2
184    copy_backward(BidirectionalIterator1 first, BidirectionalIterator1 last,
185                  BidirectionalIterator2 result);
186
187template <class ForwardIterator1, class ForwardIterator2>
188    ForwardIterator2
189    swap_ranges(ForwardIterator1 first1, ForwardIterator1 last1, ForwardIterator2 first2);
190
191template <class ForwardIterator1, class ForwardIterator2>
192    void
193    iter_swap(ForwardIterator1 a, ForwardIterator2 b);
194
195template <class InputIterator, class OutputIterator, class UnaryOperation>
196    constexpr OutputIterator      // constexpr in C++20
197    transform(InputIterator first, InputIterator last, OutputIterator result, UnaryOperation op);
198
199template <class InputIterator1, class InputIterator2, class OutputIterator, class BinaryOperation>
200    constexpr OutputIterator      // constexpr in C++20
201    transform(InputIterator1 first1, InputIterator1 last1, InputIterator2 first2,
202              OutputIterator result, BinaryOperation binary_op);
203
204template <class ForwardIterator, class T>
205    constexpr void      // constexpr in C++20
206    replace(ForwardIterator first, ForwardIterator last, const T& old_value, const T& new_value);
207
208template <class ForwardIterator, class Predicate, class T>
209    constexpr void      // constexpr in C++20
210    replace_if(ForwardIterator first, ForwardIterator last, Predicate pred, const T& new_value);
211
212template <class InputIterator, class OutputIterator, class T>
213    constexpr OutputIterator      // constexpr in C++20
214    replace_copy(InputIterator first, InputIterator last, OutputIterator result,
215                 const T& old_value, const T& new_value);
216
217template <class InputIterator, class OutputIterator, class Predicate, class T>
218    constexpr OutputIterator      // constexpr in C++20
219    replace_copy_if(InputIterator first, InputIterator last, OutputIterator result, Predicate pred, const T& new_value);
220
221template <class ForwardIterator, class T>
222    constexpr void      // constexpr in C++20
223    fill(ForwardIterator first, ForwardIterator last, const T& value);
224
225template <class OutputIterator, class Size, class T>
226    constexpr OutputIterator      // constexpr in C++20
227    fill_n(OutputIterator first, Size n, const T& value);
228
229template <class ForwardIterator, class Generator>
230    constexpr void      // constexpr in C++20
231    generate(ForwardIterator first, ForwardIterator last, Generator gen);
232
233template <class OutputIterator, class Size, class Generator>
234    constexpr OutputIterator      // constexpr in C++20
235    generate_n(OutputIterator first, Size n, Generator gen);
236
237template <class ForwardIterator, class T>
238    constexpr ForwardIterator     // constexpr in C++20
239    remove(ForwardIterator first, ForwardIterator last, const T& value);
240
241template <class ForwardIterator, class Predicate>
242    constexpr ForwardIterator     // constexpr in C++20
243    remove_if(ForwardIterator first, ForwardIterator last, Predicate pred);
244
245template <class InputIterator, class OutputIterator, class T>
246    constexpr OutputIterator     // constexpr in C++20
247    remove_copy(InputIterator first, InputIterator last, OutputIterator result, const T& value);
248
249template <class InputIterator, class OutputIterator, class Predicate>
250    constexpr OutputIterator     // constexpr in C++20
251    remove_copy_if(InputIterator first, InputIterator last, OutputIterator result, Predicate pred);
252
253template <class ForwardIterator>
254    ForwardIterator
255    unique(ForwardIterator first, ForwardIterator last);
256
257template <class ForwardIterator, class BinaryPredicate>
258    ForwardIterator
259    unique(ForwardIterator first, ForwardIterator last, BinaryPredicate pred);
260
261template <class InputIterator, class OutputIterator>
262    OutputIterator
263    unique_copy(InputIterator first, InputIterator last, OutputIterator result);
264
265template <class InputIterator, class OutputIterator, class BinaryPredicate>
266    OutputIterator
267    unique_copy(InputIterator first, InputIterator last, OutputIterator result, BinaryPredicate pred);
268
269template <class BidirectionalIterator>
270    void
271    reverse(BidirectionalIterator first, BidirectionalIterator last);
272
273template <class BidirectionalIterator, class OutputIterator>
274    constexpr OutputIterator       // constexpr in C++20
275    reverse_copy(BidirectionalIterator first, BidirectionalIterator last, OutputIterator result);
276
277template <class ForwardIterator>
278    ForwardIterator
279    rotate(ForwardIterator first, ForwardIterator middle, ForwardIterator last);
280
281template <class ForwardIterator, class OutputIterator>
282    OutputIterator
283    rotate_copy(ForwardIterator first, ForwardIterator middle, ForwardIterator last, OutputIterator result);
284
285template <class RandomAccessIterator>
286    void
287    random_shuffle(RandomAccessIterator first, RandomAccessIterator last); // deprecated in C++14, removed in C++17
288
289template <class RandomAccessIterator, class RandomNumberGenerator>
290    void
291    random_shuffle(RandomAccessIterator first, RandomAccessIterator last,
292                   RandomNumberGenerator& rand);  // deprecated in C++14, removed in C++17
293
294template<class PopulationIterator, class SampleIterator,
295         class Distance, class UniformRandomBitGenerator>
296    SampleIterator sample(PopulationIterator first, PopulationIterator last,
297                          SampleIterator out, Distance n,
298                          UniformRandomBitGenerator&& g); // C++17
299
300template<class RandomAccessIterator, class UniformRandomNumberGenerator>
301    void shuffle(RandomAccessIterator first, RandomAccessIterator last,
302                 UniformRandomNumberGenerator&& g);
303
304template <class InputIterator, class Predicate>
305    constexpr bool  // constexpr in C++20
306    is_partitioned(InputIterator first, InputIterator last, Predicate pred);
307
308template <class ForwardIterator, class Predicate>
309    ForwardIterator
310    partition(ForwardIterator first, ForwardIterator last, Predicate pred);
311
312template <class InputIterator, class OutputIterator1,
313          class OutputIterator2, class Predicate>
314    constexpr pair<OutputIterator1, OutputIterator2>   // constexpr in C++20
315    partition_copy(InputIterator first, InputIterator last,
316                   OutputIterator1 out_true, OutputIterator2 out_false,
317                   Predicate pred);
318
319template <class ForwardIterator, class Predicate>
320    ForwardIterator
321    stable_partition(ForwardIterator first, ForwardIterator last, Predicate pred);
322
323template<class ForwardIterator, class Predicate>
324    constexpr ForwardIterator  // constexpr in C++20
325    partition_point(ForwardIterator first, ForwardIterator last, Predicate pred);
326
327template <class ForwardIterator>
328    constexpr bool  // constexpr in C++20
329    is_sorted(ForwardIterator first, ForwardIterator last);
330
331template <class ForwardIterator, class Compare>
332    bool
333    is_sorted(ForwardIterator first, ForwardIterator last, Compare comp);
334
335template<class ForwardIterator>
336    constexpr ForwardIterator    // constexpr in C++20
337    is_sorted_until(ForwardIterator first, ForwardIterator last);
338
339template <class ForwardIterator, class Compare>
340    constexpr ForwardIterator    // constexpr in C++20
341    is_sorted_until(ForwardIterator first, ForwardIterator last, Compare comp);
342
343template <class RandomAccessIterator>
344    void
345    sort(RandomAccessIterator first, RandomAccessIterator last);
346
347template <class RandomAccessIterator, class Compare>
348    void
349    sort(RandomAccessIterator first, RandomAccessIterator last, Compare comp);
350
351template <class RandomAccessIterator>
352    void
353    stable_sort(RandomAccessIterator first, RandomAccessIterator last);
354
355template <class RandomAccessIterator, class Compare>
356    void
357    stable_sort(RandomAccessIterator first, RandomAccessIterator last, Compare comp);
358
359template <class RandomAccessIterator>
360    void
361    partial_sort(RandomAccessIterator first, RandomAccessIterator middle, RandomAccessIterator last);
362
363template <class RandomAccessIterator, class Compare>
364    void
365    partial_sort(RandomAccessIterator first, RandomAccessIterator middle, RandomAccessIterator last, Compare comp);
366
367template <class InputIterator, class RandomAccessIterator>
368    RandomAccessIterator
369    partial_sort_copy(InputIterator first, InputIterator last,
370                      RandomAccessIterator result_first, RandomAccessIterator result_last);
371
372template <class InputIterator, class RandomAccessIterator, class Compare>
373    RandomAccessIterator
374    partial_sort_copy(InputIterator first, InputIterator last,
375                      RandomAccessIterator result_first, RandomAccessIterator result_last, Compare comp);
376
377template <class RandomAccessIterator>
378    void
379    nth_element(RandomAccessIterator first, RandomAccessIterator nth, RandomAccessIterator last);
380
381template <class RandomAccessIterator, class Compare>
382    void
383    nth_element(RandomAccessIterator first, RandomAccessIterator nth, RandomAccessIterator last, Compare comp);
384
385template <class ForwardIterator, class T>
386    constexpr ForwardIterator                         // constexpr in C++20
387    lower_bound(ForwardIterator first, ForwardIterator last, const T& value);
388
389template <class ForwardIterator, class T, class Compare>
390    constexpr ForwardIterator                         // constexpr in C++20
391    lower_bound(ForwardIterator first, ForwardIterator last, const T& value, Compare comp);
392
393template <class ForwardIterator, class T>
394    constexpr ForwardIterator                         // constexpr in C++20
395    upper_bound(ForwardIterator first, ForwardIterator last, const T& value);
396
397template <class ForwardIterator, class T, class Compare>
398    constexpr ForwardIterator                         // constexpr in C++20
399    upper_bound(ForwardIterator first, ForwardIterator last, const T& value, Compare comp);
400
401template <class ForwardIterator, class T>
402    constexpr pair<ForwardIterator, ForwardIterator>  // constexpr in C++20
403    equal_range(ForwardIterator first, ForwardIterator last, const T& value);
404
405template <class ForwardIterator, class T, class Compare>
406    constexpr pair<ForwardIterator, ForwardIterator>  // constexpr in C++20
407    equal_range(ForwardIterator first, ForwardIterator last, const T& value, Compare comp);
408
409template <class ForwardIterator, class T>
410    constexpr bool                                    // constexpr in C++20
411    binary_search(ForwardIterator first, ForwardIterator last, const T& value);
412
413template <class ForwardIterator, class T, class Compare>
414    constexpr bool                                    // constexpr in C++20
415    binary_search(ForwardIterator first, ForwardIterator last, const T& value, Compare comp);
416
417template <class InputIterator1, class InputIterator2, class OutputIterator>
418    OutputIterator
419    merge(InputIterator1 first1, InputIterator1 last1,
420          InputIterator2 first2, InputIterator2 last2, OutputIterator result);
421
422template <class InputIterator1, class InputIterator2, class OutputIterator, class Compare>
423    OutputIterator
424    merge(InputIterator1 first1, InputIterator1 last1,
425          InputIterator2 first2, InputIterator2 last2, OutputIterator result, Compare comp);
426
427template <class BidirectionalIterator>
428    void
429    inplace_merge(BidirectionalIterator first, BidirectionalIterator middle, BidirectionalIterator last);
430
431template <class BidirectionalIterator, class Compare>
432    void
433    inplace_merge(BidirectionalIterator first, BidirectionalIterator middle, BidirectionalIterator last, Compare comp);
434
435template <class InputIterator1, class InputIterator2>
436    constexpr bool                                    // constexpr in C++20
437    includes(InputIterator1 first1, InputIterator1 last1, InputIterator2 first2, InputIterator2 last2);
438
439template <class InputIterator1, class InputIterator2, class Compare>
440    constexpr bool                                    // constexpr in C++20
441    includes(InputIterator1 first1, InputIterator1 last1, InputIterator2 first2, InputIterator2 last2, Compare comp);
442
443template <class InputIterator1, class InputIterator2, class OutputIterator>
444    OutputIterator
445    set_union(InputIterator1 first1, InputIterator1 last1,
446              InputIterator2 first2, InputIterator2 last2, OutputIterator result);
447
448template <class InputIterator1, class InputIterator2, class OutputIterator, class Compare>
449    OutputIterator
450    set_union(InputIterator1 first1, InputIterator1 last1,
451              InputIterator2 first2, InputIterator2 last2, OutputIterator result, Compare comp);
452
453template <class InputIterator1, class InputIterator2, class OutputIterator>
454    constexpr OutputIterator                         // constexpr in C++20
455    set_intersection(InputIterator1 first1, InputIterator1 last1,
456                     InputIterator2 first2, InputIterator2 last2, OutputIterator result);
457
458template <class InputIterator1, class InputIterator2, class OutputIterator, class Compare>
459    constexpr OutputIterator                         // constexpr in C++20
460    set_intersection(InputIterator1 first1, InputIterator1 last1,
461                     InputIterator2 first2, InputIterator2 last2, OutputIterator result, Compare comp);
462
463template <class InputIterator1, class InputIterator2, class OutputIterator>
464    OutputIterator
465    set_difference(InputIterator1 first1, InputIterator1 last1,
466                   InputIterator2 first2, InputIterator2 last2, OutputIterator result);
467
468template <class InputIterator1, class InputIterator2, class OutputIterator, class Compare>
469    OutputIterator
470    set_difference(InputIterator1 first1, InputIterator1 last1,
471                   InputIterator2 first2, InputIterator2 last2, OutputIterator result, Compare comp);
472
473template <class InputIterator1, class InputIterator2, class OutputIterator>
474    OutputIterator
475    set_symmetric_difference(InputIterator1 first1, InputIterator1 last1,
476                             InputIterator2 first2, InputIterator2 last2, OutputIterator result);
477
478template <class InputIterator1, class InputIterator2, class OutputIterator, class Compare>
479    OutputIterator
480    set_symmetric_difference(InputIterator1 first1, InputIterator1 last1,
481                             InputIterator2 first2, InputIterator2 last2, OutputIterator result, Compare comp);
482
483template <class RandomAccessIterator>
484    void
485    push_heap(RandomAccessIterator first, RandomAccessIterator last);
486
487template <class RandomAccessIterator, class Compare>
488    void
489    push_heap(RandomAccessIterator first, RandomAccessIterator last, Compare comp);
490
491template <class RandomAccessIterator>
492    void
493    pop_heap(RandomAccessIterator first, RandomAccessIterator last);
494
495template <class RandomAccessIterator, class Compare>
496    void
497    pop_heap(RandomAccessIterator first, RandomAccessIterator last, Compare comp);
498
499template <class RandomAccessIterator>
500    void
501    make_heap(RandomAccessIterator first, RandomAccessIterator last);
502
503template <class RandomAccessIterator, class Compare>
504    void
505    make_heap(RandomAccessIterator first, RandomAccessIterator last, Compare comp);
506
507template <class RandomAccessIterator>
508    void
509    sort_heap(RandomAccessIterator first, RandomAccessIterator last);
510
511template <class RandomAccessIterator, class Compare>
512    void
513    sort_heap(RandomAccessIterator first, RandomAccessIterator last, Compare comp);
514
515template <class RandomAccessIterator>
516    constexpr bool   // constexpr in C++20
517    is_heap(RandomAccessIterator first, RandomAccessiterator last);
518
519template <class RandomAccessIterator, class Compare>
520    constexpr bool   // constexpr in C++20
521    is_heap(RandomAccessIterator first, RandomAccessiterator last, Compare comp);
522
523template <class RandomAccessIterator>
524    constexpr RandomAccessIterator   // constexpr in C++20
525    is_heap_until(RandomAccessIterator first, RandomAccessiterator last);
526
527template <class RandomAccessIterator, class Compare>
528    constexpr RandomAccessIterator   // constexpr in C++20
529    is_heap_until(RandomAccessIterator first, RandomAccessiterator last, Compare comp);
530
531template <class ForwardIterator>
532    ForwardIterator
533    min_element(ForwardIterator first, ForwardIterator last);  // constexpr in C++14
534
535template <class ForwardIterator, class Compare>
536    ForwardIterator
537    min_element(ForwardIterator first, ForwardIterator last, Compare comp);  // constexpr in C++14
538
539template <class T>
540    const T&
541    min(const T& a, const T& b);  // constexpr in C++14
542
543template <class T, class Compare>
544    const T&
545    min(const T& a, const T& b, Compare comp);  // constexpr in C++14
546
547template<class T>
548    T
549    min(initializer_list<T> t);  // constexpr in C++14
550
551template<class T, class Compare>
552    T
553    min(initializer_list<T> t, Compare comp);  // constexpr in C++14
554
555template<class T>
556    constexpr const T& clamp( const T& v, const T& lo, const T& hi );               // C++17
557
558template<class T, class Compare>
559    constexpr const T& clamp( const T& v, const T& lo, const T& hi, Compare comp ); // C++17
560
561template <class ForwardIterator>
562    ForwardIterator
563    max_element(ForwardIterator first, ForwardIterator last);  // constexpr in C++14
564
565template <class ForwardIterator, class Compare>
566    ForwardIterator
567    max_element(ForwardIterator first, ForwardIterator last, Compare comp);  // constexpr in C++14
568
569template <class T>
570    const T&
571    max(const T& a, const T& b); // constexpr in C++14
572
573template <class T, class Compare>
574    const T&
575    max(const T& a, const T& b, Compare comp);  // constexpr in C++14
576
577template<class T>
578    T
579    max(initializer_list<T> t);  // constexpr in C++14
580
581template<class T, class Compare>
582    T
583    max(initializer_list<T> t, Compare comp);  // constexpr in C++14
584
585template<class ForwardIterator>
586    pair<ForwardIterator, ForwardIterator>
587    minmax_element(ForwardIterator first, ForwardIterator last);   // constexpr in C++14
588
589template<class ForwardIterator, class Compare>
590    pair<ForwardIterator, ForwardIterator>
591    minmax_element(ForwardIterator first, ForwardIterator last, Compare comp);   // constexpr in C++14
592
593template<class T>
594    pair<const T&, const T&>
595    minmax(const T& a, const T& b);  // constexpr in C++14
596
597template<class T, class Compare>
598    pair<const T&, const T&>
599    minmax(const T& a, const T& b, Compare comp);  // constexpr in C++14
600
601template<class T>
602    pair<T, T>
603    minmax(initializer_list<T> t);  // constexpr in C++14
604
605template<class T, class Compare>
606    pair<T, T>
607    minmax(initializer_list<T> t, Compare comp);  // constexpr in C++14
608
609template <class InputIterator1, class InputIterator2>
610    constexpr bool     // constexpr in C++20
611    lexicographical_compare(InputIterator1 first1, InputIterator1 last1, InputIterator2 first2, InputIterator2 last2);
612
613template <class InputIterator1, class InputIterator2, class Compare>
614    constexpr bool     // constexpr in C++20
615    lexicographical_compare(InputIterator1 first1, InputIterator1 last1,
616                            InputIterator2 first2, InputIterator2 last2, Compare comp);
617
618template <class BidirectionalIterator>
619    bool
620    next_permutation(BidirectionalIterator first, BidirectionalIterator last);
621
622template <class BidirectionalIterator, class Compare>
623    bool
624    next_permutation(BidirectionalIterator first, BidirectionalIterator last, Compare comp);
625
626template <class BidirectionalIterator>
627    bool
628    prev_permutation(BidirectionalIterator first, BidirectionalIterator last);
629
630template <class BidirectionalIterator, class Compare>
631    bool
632    prev_permutation(BidirectionalIterator first, BidirectionalIterator last, Compare comp);
633
634}  // std
635
636*/
637
638#include <__config>
639#include <initializer_list>
640#include <type_traits>
641#include <cstring>
642#include <utility> // needed to provide swap_ranges.
643#include <memory>
644#include <functional>
645#include <iterator>
646#include <cstddef>
647#include <bit>
648#include <version>
649
650#include <__debug>
651
652#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
653#pragma GCC system_header
654#endif
655
656_LIBCPP_PUSH_MACROS
657#include <__undef_macros>
658
659
660_LIBCPP_BEGIN_NAMESPACE_STD
661
662// I'd like to replace these with _VSTD::equal_to<void>, but can't because:
663//   * That only works with C++14 and later, and
664//   * We haven't included <functional> here.
665template <class _T1, class _T2 = _T1>
666struct __equal_to
667{
668    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11 bool operator()(const _T1& __x, const _T1& __y) const {return __x == __y;}
669    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11 bool operator()(const _T1& __x, const _T2& __y) const {return __x == __y;}
670    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11 bool operator()(const _T2& __x, const _T1& __y) const {return __x == __y;}
671    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11 bool operator()(const _T2& __x, const _T2& __y) const {return __x == __y;}
672};
673
674template <class _T1>
675struct __equal_to<_T1, _T1>
676{
677    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
678    bool operator()(const _T1& __x, const _T1& __y) const {return __x == __y;}
679};
680
681template <class _T1>
682struct __equal_to<const _T1, _T1>
683{
684    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
685    bool operator()(const _T1& __x, const _T1& __y) const {return __x == __y;}
686};
687
688template <class _T1>
689struct __equal_to<_T1, const _T1>
690{
691    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
692    bool operator()(const _T1& __x, const _T1& __y) const {return __x == __y;}
693};
694
695template <class _T1, class _T2 = _T1>
696struct __less
697{
698    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
699    bool operator()(const _T1& __x, const _T1& __y) const {return __x < __y;}
700
701    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
702    bool operator()(const _T1& __x, const _T2& __y) const {return __x < __y;}
703
704    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
705    bool operator()(const _T2& __x, const _T1& __y) const {return __x < __y;}
706
707    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
708    bool operator()(const _T2& __x, const _T2& __y) const {return __x < __y;}
709};
710
711template <class _T1>
712struct __less<_T1, _T1>
713{
714    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
715    bool operator()(const _T1& __x, const _T1& __y) const {return __x < __y;}
716};
717
718template <class _T1>
719struct __less<const _T1, _T1>
720{
721    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
722    bool operator()(const _T1& __x, const _T1& __y) const {return __x < __y;}
723};
724
725template <class _T1>
726struct __less<_T1, const _T1>
727{
728    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
729    bool operator()(const _T1& __x, const _T1& __y) const {return __x < __y;}
730};
731
732template <class _Predicate>
733class __invert // invert the sense of a comparison
734{
735private:
736    _Predicate __p_;
737public:
738    _LIBCPP_INLINE_VISIBILITY __invert() {}
739
740    _LIBCPP_INLINE_VISIBILITY
741    explicit __invert(_Predicate __p) : __p_(__p) {}
742
743    template <class _T1>
744    _LIBCPP_INLINE_VISIBILITY
745    bool operator()(const _T1& __x) {return !__p_(__x);}
746
747    template <class _T1, class _T2>
748    _LIBCPP_INLINE_VISIBILITY
749    bool operator()(const _T1& __x, const _T2& __y) {return __p_(__y, __x);}
750};
751
752// Perform division by two quickly for positive integers (llvm.org/PR39129)
753
754template <typename _Integral>
755_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
756typename enable_if
757<
758    is_integral<_Integral>::value,
759    _Integral
760>::type
761__half_positive(_Integral __value)
762{
763    return static_cast<_Integral>(static_cast<typename make_unsigned<_Integral>::type>(__value) / 2);
764}
765
766template <typename _Tp>
767_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
768typename enable_if
769<
770    !is_integral<_Tp>::value,
771    _Tp
772>::type
773__half_positive(_Tp __value)
774{
775    return __value / 2;
776}
777
778#ifdef _LIBCPP_DEBUG
779
780template <class _Compare>
781struct __debug_less
782{
783    _Compare &__comp_;
784    _LIBCPP_CONSTEXPR_AFTER_CXX17
785    __debug_less(_Compare& __c) : __comp_(__c) {}
786
787    template <class _Tp, class _Up>
788    bool operator()(const _Tp& __x,  const _Up& __y)
789    {
790        bool __r = __comp_(__x, __y);
791        if (__r)
792            __do_compare_assert(0, __y, __x);
793        return __r;
794    }
795
796    template <class _Tp, class _Up>
797    _LIBCPP_CONSTEXPR_AFTER_CXX17
798    bool operator()(_Tp& __x,  _Up& __y)
799    {
800        bool __r = __comp_(__x, __y);
801        if (__r)
802            __do_compare_assert(0, __y, __x);
803        return __r;
804    }
805
806    template <class _LHS, class _RHS>
807    _LIBCPP_CONSTEXPR_AFTER_CXX17
808    inline _LIBCPP_INLINE_VISIBILITY
809    decltype((void)_VSTD::declval<_Compare&>()(
810        _VSTD::declval<_LHS &>(), _VSTD::declval<_RHS &>()))
811    __do_compare_assert(int, _LHS & __l, _RHS & __r) {
812        _LIBCPP_ASSERT(!__comp_(__l, __r),
813            "Comparator does not induce a strict weak ordering");
814    }
815
816    template <class _LHS, class _RHS>
817    _LIBCPP_CONSTEXPR_AFTER_CXX17
818    inline _LIBCPP_INLINE_VISIBILITY
819    void __do_compare_assert(long, _LHS &, _RHS &) {}
820};
821
822#endif // _LIBCPP_DEBUG
823
824template <class _Comp>
825struct __comp_ref_type {
826  // Pass the comparator by lvalue reference. Or in debug mode, using a
827  // debugging wrapper that stores a reference.
828#ifndef _LIBCPP_DEBUG
829  typedef typename add_lvalue_reference<_Comp>::type type;
830#else
831  typedef __debug_less<_Comp> type;
832#endif
833};
834
835// all_of
836
837template <class _InputIterator, class _Predicate>
838_LIBCPP_NODISCARD_EXT inline
839_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
840bool
841all_of(_InputIterator __first, _InputIterator __last, _Predicate __pred)
842{
843    for (; __first != __last; ++__first)
844        if (!__pred(*__first))
845            return false;
846    return true;
847}
848
849// any_of
850
851template <class _InputIterator, class _Predicate>
852_LIBCPP_NODISCARD_EXT inline
853_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
854bool
855any_of(_InputIterator __first, _InputIterator __last, _Predicate __pred)
856{
857    for (; __first != __last; ++__first)
858        if (__pred(*__first))
859            return true;
860    return false;
861}
862
863// none_of
864
865template <class _InputIterator, class _Predicate>
866_LIBCPP_NODISCARD_EXT inline
867_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
868bool
869none_of(_InputIterator __first, _InputIterator __last, _Predicate __pred)
870{
871    for (; __first != __last; ++__first)
872        if (__pred(*__first))
873            return false;
874    return true;
875}
876
877// for_each
878
879template <class _InputIterator, class _Function>
880inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
881_Function
882for_each(_InputIterator __first, _InputIterator __last, _Function __f)
883{
884    for (; __first != __last; ++__first)
885        __f(*__first);
886    return __f;
887}
888
889#if _LIBCPP_STD_VER > 14
890// for_each_n
891
892template <class _InputIterator, class _Size, class _Function>
893inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
894_InputIterator
895for_each_n(_InputIterator __first, _Size __orig_n, _Function __f)
896{
897    typedef decltype(__convert_to_integral(__orig_n)) _IntegralSize;
898    _IntegralSize __n = __orig_n;
899    while (__n > 0)
900    {
901         __f(*__first);
902         ++__first;
903         --__n;
904    }
905    return __first;
906}
907#endif
908
909// find
910
911template <class _InputIterator, class _Tp>
912_LIBCPP_NODISCARD_EXT inline
913_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
914_InputIterator
915find(_InputIterator __first, _InputIterator __last, const _Tp& __value_)
916{
917    for (; __first != __last; ++__first)
918        if (*__first == __value_)
919            break;
920    return __first;
921}
922
923// find_if
924
925template <class _InputIterator, class _Predicate>
926_LIBCPP_NODISCARD_EXT inline
927_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
928_InputIterator
929find_if(_InputIterator __first, _InputIterator __last, _Predicate __pred)
930{
931    for (; __first != __last; ++__first)
932        if (__pred(*__first))
933            break;
934    return __first;
935}
936
937// find_if_not
938
939template<class _InputIterator, class _Predicate>
940_LIBCPP_NODISCARD_EXT inline
941_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
942_InputIterator
943find_if_not(_InputIterator __first, _InputIterator __last, _Predicate __pred)
944{
945    for (; __first != __last; ++__first)
946        if (!__pred(*__first))
947            break;
948    return __first;
949}
950
951// find_end
952
953template <class _BinaryPredicate, class _ForwardIterator1, class _ForwardIterator2>
954_LIBCPP_CONSTEXPR_AFTER_CXX17 _ForwardIterator1
955__find_end(_ForwardIterator1 __first1, _ForwardIterator1 __last1,
956           _ForwardIterator2 __first2, _ForwardIterator2 __last2, _BinaryPredicate __pred,
957           forward_iterator_tag, forward_iterator_tag)
958{
959    // modeled after search algorithm
960    _ForwardIterator1 __r = __last1;  // __last1 is the "default" answer
961    if (__first2 == __last2)
962        return __r;
963    while (true)
964    {
965        while (true)
966        {
967            if (__first1 == __last1)         // if source exhausted return last correct answer
968                return __r;                  //    (or __last1 if never found)
969            if (__pred(*__first1, *__first2))
970                break;
971            ++__first1;
972        }
973        // *__first1 matches *__first2, now match elements after here
974        _ForwardIterator1 __m1 = __first1;
975        _ForwardIterator2 __m2 = __first2;
976        while (true)
977        {
978            if (++__m2 == __last2)
979            {                         // Pattern exhaused, record answer and search for another one
980                __r = __first1;
981                ++__first1;
982                break;
983            }
984            if (++__m1 == __last1)     // Source exhausted, return last answer
985                return __r;
986            if (!__pred(*__m1, *__m2))  // mismatch, restart with a new __first
987            {
988                ++__first1;
989                break;
990            }  // else there is a match, check next elements
991        }
992    }
993}
994
995template <class _BinaryPredicate, class _BidirectionalIterator1, class _BidirectionalIterator2>
996_LIBCPP_CONSTEXPR_AFTER_CXX17 _BidirectionalIterator1
997__find_end(_BidirectionalIterator1 __first1, _BidirectionalIterator1 __last1,
998           _BidirectionalIterator2 __first2, _BidirectionalIterator2 __last2, _BinaryPredicate __pred,
999           bidirectional_iterator_tag, bidirectional_iterator_tag)
1000{
1001    // modeled after search algorithm (in reverse)
1002    if (__first2 == __last2)
1003        return __last1;  // Everything matches an empty sequence
1004    _BidirectionalIterator1 __l1 = __last1;
1005    _BidirectionalIterator2 __l2 = __last2;
1006    --__l2;
1007    while (true)
1008    {
1009        // Find last element in sequence 1 that matchs *(__last2-1), with a mininum of loop checks
1010        while (true)
1011        {
1012            if (__first1 == __l1)  // return __last1 if no element matches *__first2
1013                return __last1;
1014            if (__pred(*--__l1, *__l2))
1015                break;
1016        }
1017        // *__l1 matches *__l2, now match elements before here
1018        _BidirectionalIterator1 __m1 = __l1;
1019        _BidirectionalIterator2 __m2 = __l2;
1020        while (true)
1021        {
1022            if (__m2 == __first2)  // If pattern exhausted, __m1 is the answer (works for 1 element pattern)
1023                return __m1;
1024            if (__m1 == __first1)  // Otherwise if source exhaused, pattern not found
1025                return __last1;
1026            if (!__pred(*--__m1, *--__m2))  // if there is a mismatch, restart with a new __l1
1027            {
1028                break;
1029            }  // else there is a match, check next elements
1030        }
1031    }
1032}
1033
1034template <class _BinaryPredicate, class _RandomAccessIterator1, class _RandomAccessIterator2>
1035_LIBCPP_CONSTEXPR_AFTER_CXX11 _RandomAccessIterator1
1036__find_end(_RandomAccessIterator1 __first1, _RandomAccessIterator1 __last1,
1037           _RandomAccessIterator2 __first2, _RandomAccessIterator2 __last2, _BinaryPredicate __pred,
1038           random_access_iterator_tag, random_access_iterator_tag)
1039{
1040    // Take advantage of knowing source and pattern lengths.  Stop short when source is smaller than pattern
1041    typename iterator_traits<_RandomAccessIterator2>::difference_type __len2 = __last2 - __first2;
1042    if (__len2 == 0)
1043        return __last1;
1044    typename iterator_traits<_RandomAccessIterator1>::difference_type __len1 = __last1 - __first1;
1045    if (__len1 < __len2)
1046        return __last1;
1047    const _RandomAccessIterator1 __s = __first1 + (__len2 - 1);  // End of pattern match can't go before here
1048    _RandomAccessIterator1 __l1 = __last1;
1049    _RandomAccessIterator2 __l2 = __last2;
1050    --__l2;
1051    while (true)
1052    {
1053        while (true)
1054        {
1055            if (__s == __l1)
1056                return __last1;
1057            if (__pred(*--__l1, *__l2))
1058                break;
1059        }
1060        _RandomAccessIterator1 __m1 = __l1;
1061        _RandomAccessIterator2 __m2 = __l2;
1062        while (true)
1063        {
1064            if (__m2 == __first2)
1065                return __m1;
1066                                 // no need to check range on __m1 because __s guarantees we have enough source
1067            if (!__pred(*--__m1, *--__m2))
1068            {
1069                break;
1070            }
1071        }
1072    }
1073}
1074
1075template <class _ForwardIterator1, class _ForwardIterator2, class _BinaryPredicate>
1076_LIBCPP_NODISCARD_EXT inline
1077_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
1078_ForwardIterator1
1079find_end(_ForwardIterator1 __first1, _ForwardIterator1 __last1,
1080         _ForwardIterator2 __first2, _ForwardIterator2 __last2, _BinaryPredicate __pred)
1081{
1082    return _VSTD::__find_end<typename add_lvalue_reference<_BinaryPredicate>::type>
1083                         (__first1, __last1, __first2, __last2, __pred,
1084                          typename iterator_traits<_ForwardIterator1>::iterator_category(),
1085                          typename iterator_traits<_ForwardIterator2>::iterator_category());
1086}
1087
1088template <class _ForwardIterator1, class _ForwardIterator2>
1089_LIBCPP_NODISCARD_EXT inline
1090_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
1091_ForwardIterator1
1092find_end(_ForwardIterator1 __first1, _ForwardIterator1 __last1,
1093         _ForwardIterator2 __first2, _ForwardIterator2 __last2)
1094{
1095    typedef typename iterator_traits<_ForwardIterator1>::value_type __v1;
1096    typedef typename iterator_traits<_ForwardIterator2>::value_type __v2;
1097    return _VSTD::find_end(__first1, __last1, __first2, __last2, __equal_to<__v1, __v2>());
1098}
1099
1100// find_first_of
1101
1102template <class _ForwardIterator1, class _ForwardIterator2, class _BinaryPredicate>
1103_LIBCPP_CONSTEXPR_AFTER_CXX11 _ForwardIterator1
1104__find_first_of_ce(_ForwardIterator1 __first1, _ForwardIterator1 __last1,
1105              _ForwardIterator2 __first2, _ForwardIterator2 __last2, _BinaryPredicate __pred)
1106{
1107    for (; __first1 != __last1; ++__first1)
1108        for (_ForwardIterator2 __j = __first2; __j != __last2; ++__j)
1109            if (__pred(*__first1, *__j))
1110                return __first1;
1111    return __last1;
1112}
1113
1114
1115template <class _ForwardIterator1, class _ForwardIterator2, class _BinaryPredicate>
1116_LIBCPP_NODISCARD_EXT inline
1117_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
1118_ForwardIterator1
1119find_first_of(_ForwardIterator1 __first1, _ForwardIterator1 __last1,
1120              _ForwardIterator2 __first2, _ForwardIterator2 __last2, _BinaryPredicate __pred)
1121{
1122    return _VSTD::__find_first_of_ce(__first1, __last1, __first2, __last2, __pred);
1123}
1124
1125template <class _ForwardIterator1, class _ForwardIterator2>
1126_LIBCPP_NODISCARD_EXT inline
1127_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
1128_ForwardIterator1
1129find_first_of(_ForwardIterator1 __first1, _ForwardIterator1 __last1,
1130              _ForwardIterator2 __first2, _ForwardIterator2 __last2)
1131{
1132    typedef typename iterator_traits<_ForwardIterator1>::value_type __v1;
1133    typedef typename iterator_traits<_ForwardIterator2>::value_type __v2;
1134    return _VSTD::__find_first_of_ce(__first1, __last1, __first2, __last2, __equal_to<__v1, __v2>());
1135}
1136
1137// adjacent_find
1138
1139template <class _ForwardIterator, class _BinaryPredicate>
1140_LIBCPP_NODISCARD_EXT inline
1141_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
1142_ForwardIterator
1143adjacent_find(_ForwardIterator __first, _ForwardIterator __last, _BinaryPredicate __pred)
1144{
1145    if (__first != __last)
1146    {
1147        _ForwardIterator __i = __first;
1148        while (++__i != __last)
1149        {
1150            if (__pred(*__first, *__i))
1151                return __first;
1152            __first = __i;
1153        }
1154    }
1155    return __last;
1156}
1157
1158template <class _ForwardIterator>
1159_LIBCPP_NODISCARD_EXT inline
1160_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
1161_ForwardIterator
1162adjacent_find(_ForwardIterator __first, _ForwardIterator __last)
1163{
1164    typedef typename iterator_traits<_ForwardIterator>::value_type __v;
1165    return _VSTD::adjacent_find(__first, __last, __equal_to<__v>());
1166}
1167
1168// count
1169
1170template <class _InputIterator, class _Tp>
1171_LIBCPP_NODISCARD_EXT inline
1172_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
1173typename iterator_traits<_InputIterator>::difference_type
1174count(_InputIterator __first, _InputIterator __last, const _Tp& __value_)
1175{
1176    typename iterator_traits<_InputIterator>::difference_type __r(0);
1177    for (; __first != __last; ++__first)
1178        if (*__first == __value_)
1179            ++__r;
1180    return __r;
1181}
1182
1183// count_if
1184
1185template <class _InputIterator, class _Predicate>
1186_LIBCPP_NODISCARD_EXT inline
1187_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
1188typename iterator_traits<_InputIterator>::difference_type
1189count_if(_InputIterator __first, _InputIterator __last, _Predicate __pred)
1190{
1191    typename iterator_traits<_InputIterator>::difference_type __r(0);
1192    for (; __first != __last; ++__first)
1193        if (__pred(*__first))
1194            ++__r;
1195    return __r;
1196}
1197
1198// mismatch
1199
1200template <class _InputIterator1, class _InputIterator2, class _BinaryPredicate>
1201_LIBCPP_NODISCARD_EXT inline
1202_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
1203pair<_InputIterator1, _InputIterator2>
1204mismatch(_InputIterator1 __first1, _InputIterator1 __last1,
1205         _InputIterator2 __first2, _BinaryPredicate __pred)
1206{
1207    for (; __first1 != __last1; ++__first1, (void) ++__first2)
1208        if (!__pred(*__first1, *__first2))
1209            break;
1210    return pair<_InputIterator1, _InputIterator2>(__first1, __first2);
1211}
1212
1213template <class _InputIterator1, class _InputIterator2>
1214_LIBCPP_NODISCARD_EXT inline
1215_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
1216pair<_InputIterator1, _InputIterator2>
1217mismatch(_InputIterator1 __first1, _InputIterator1 __last1, _InputIterator2 __first2)
1218{
1219    typedef typename iterator_traits<_InputIterator1>::value_type __v1;
1220    typedef typename iterator_traits<_InputIterator2>::value_type __v2;
1221    return _VSTD::mismatch(__first1, __last1, __first2, __equal_to<__v1, __v2>());
1222}
1223
1224#if _LIBCPP_STD_VER > 11
1225template <class _InputIterator1, class _InputIterator2, class _BinaryPredicate>
1226_LIBCPP_NODISCARD_EXT inline
1227_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
1228pair<_InputIterator1, _InputIterator2>
1229mismatch(_InputIterator1 __first1, _InputIterator1 __last1,
1230         _InputIterator2 __first2, _InputIterator2 __last2,
1231         _BinaryPredicate __pred)
1232{
1233    for (; __first1 != __last1 && __first2 != __last2; ++__first1, (void) ++__first2)
1234        if (!__pred(*__first1, *__first2))
1235            break;
1236    return pair<_InputIterator1, _InputIterator2>(__first1, __first2);
1237}
1238
1239template <class _InputIterator1, class _InputIterator2>
1240_LIBCPP_NODISCARD_EXT inline
1241_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
1242pair<_InputIterator1, _InputIterator2>
1243mismatch(_InputIterator1 __first1, _InputIterator1 __last1,
1244         _InputIterator2 __first2, _InputIterator2 __last2)
1245{
1246    typedef typename iterator_traits<_InputIterator1>::value_type __v1;
1247    typedef typename iterator_traits<_InputIterator2>::value_type __v2;
1248    return _VSTD::mismatch(__first1, __last1, __first2, __last2, __equal_to<__v1, __v2>());
1249}
1250#endif
1251
1252// equal
1253
1254template <class _InputIterator1, class _InputIterator2, class _BinaryPredicate>
1255_LIBCPP_NODISCARD_EXT inline
1256_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
1257bool
1258equal(_InputIterator1 __first1, _InputIterator1 __last1, _InputIterator2 __first2, _BinaryPredicate __pred)
1259{
1260    for (; __first1 != __last1; ++__first1, (void) ++__first2)
1261        if (!__pred(*__first1, *__first2))
1262            return false;
1263    return true;
1264}
1265
1266template <class _InputIterator1, class _InputIterator2>
1267_LIBCPP_NODISCARD_EXT inline
1268_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
1269bool
1270equal(_InputIterator1 __first1, _InputIterator1 __last1, _InputIterator2 __first2)
1271{
1272    typedef typename iterator_traits<_InputIterator1>::value_type __v1;
1273    typedef typename iterator_traits<_InputIterator2>::value_type __v2;
1274    return _VSTD::equal(__first1, __last1, __first2, __equal_to<__v1, __v2>());
1275}
1276
1277#if _LIBCPP_STD_VER > 11
1278template <class _BinaryPredicate, class _InputIterator1, class _InputIterator2>
1279inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
1280bool
1281__equal(_InputIterator1 __first1, _InputIterator1 __last1,
1282        _InputIterator2 __first2, _InputIterator2 __last2, _BinaryPredicate __pred,
1283        input_iterator_tag, input_iterator_tag )
1284{
1285    for (; __first1 != __last1 && __first2 != __last2; ++__first1, (void) ++__first2)
1286        if (!__pred(*__first1, *__first2))
1287            return false;
1288    return __first1 == __last1 && __first2 == __last2;
1289}
1290
1291template <class _BinaryPredicate, class _RandomAccessIterator1, class _RandomAccessIterator2>
1292inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
1293bool
1294__equal(_RandomAccessIterator1 __first1, _RandomAccessIterator1 __last1,
1295        _RandomAccessIterator2 __first2, _RandomAccessIterator2 __last2, _BinaryPredicate __pred,
1296      random_access_iterator_tag, random_access_iterator_tag )
1297{
1298    if ( _VSTD::distance(__first1, __last1) != _VSTD::distance(__first2, __last2))
1299        return false;
1300    return _VSTD::equal<_RandomAccessIterator1, _RandomAccessIterator2,
1301                        typename add_lvalue_reference<_BinaryPredicate>::type>
1302                       (__first1, __last1, __first2, __pred );
1303}
1304
1305template <class _InputIterator1, class _InputIterator2, class _BinaryPredicate>
1306_LIBCPP_NODISCARD_EXT inline
1307_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
1308bool
1309equal(_InputIterator1 __first1, _InputIterator1 __last1,
1310      _InputIterator2 __first2, _InputIterator2 __last2, _BinaryPredicate __pred )
1311{
1312    return _VSTD::__equal<typename add_lvalue_reference<_BinaryPredicate>::type>
1313       (__first1, __last1, __first2, __last2, __pred,
1314        typename iterator_traits<_InputIterator1>::iterator_category(),
1315        typename iterator_traits<_InputIterator2>::iterator_category());
1316}
1317
1318template <class _InputIterator1, class _InputIterator2>
1319_LIBCPP_NODISCARD_EXT inline
1320_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
1321bool
1322equal(_InputIterator1 __first1, _InputIterator1 __last1,
1323      _InputIterator2 __first2, _InputIterator2 __last2)
1324{
1325    typedef typename iterator_traits<_InputIterator1>::value_type __v1;
1326    typedef typename iterator_traits<_InputIterator2>::value_type __v2;
1327    return _VSTD::__equal(__first1, __last1, __first2, __last2, __equal_to<__v1, __v2>(),
1328        typename iterator_traits<_InputIterator1>::iterator_category(),
1329        typename iterator_traits<_InputIterator2>::iterator_category());
1330}
1331#endif
1332
1333// is_permutation
1334
1335template<class _ForwardIterator1, class _ForwardIterator2, class _BinaryPredicate>
1336_LIBCPP_NODISCARD_EXT _LIBCPP_CONSTEXPR_AFTER_CXX17 bool
1337is_permutation(_ForwardIterator1 __first1, _ForwardIterator1 __last1,
1338               _ForwardIterator2 __first2, _BinaryPredicate __pred)
1339{
1340//  shorten sequences as much as possible by lopping of any equal prefix
1341    for (; __first1 != __last1; ++__first1, (void) ++__first2)
1342        if (!__pred(*__first1, *__first2))
1343            break;
1344    if (__first1 == __last1)
1345        return true;
1346
1347//  __first1 != __last1 && *__first1 != *__first2
1348    typedef typename iterator_traits<_ForwardIterator1>::difference_type _D1;
1349    _D1 __l1 = _VSTD::distance(__first1, __last1);
1350    if (__l1 == _D1(1))
1351        return false;
1352    _ForwardIterator2 __last2 = _VSTD::next(__first2, __l1);
1353    // For each element in [f1, l1) see if there are the same number of
1354    //    equal elements in [f2, l2)
1355    for (_ForwardIterator1 __i = __first1; __i != __last1; ++__i)
1356    {
1357    //  Have we already counted the number of *__i in [f1, l1)?
1358        _ForwardIterator1 __match = __first1;
1359        for (; __match != __i; ++__match)
1360            if (__pred(*__match, *__i))
1361                break;
1362        if (__match == __i) {
1363            // Count number of *__i in [f2, l2)
1364            _D1 __c2 = 0;
1365            for (_ForwardIterator2 __j = __first2; __j != __last2; ++__j)
1366                if (__pred(*__i, *__j))
1367                    ++__c2;
1368            if (__c2 == 0)
1369                return false;
1370            // Count number of *__i in [__i, l1) (we can start with 1)
1371            _D1 __c1 = 1;
1372            for (_ForwardIterator1 __j = _VSTD::next(__i); __j != __last1; ++__j)
1373                if (__pred(*__i, *__j))
1374                    ++__c1;
1375            if (__c1 != __c2)
1376                return false;
1377        }
1378    }
1379    return true;
1380}
1381
1382template<class _ForwardIterator1, class _ForwardIterator2>
1383_LIBCPP_NODISCARD_EXT inline
1384_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
1385bool
1386is_permutation(_ForwardIterator1 __first1, _ForwardIterator1 __last1,
1387               _ForwardIterator2 __first2)
1388{
1389    typedef typename iterator_traits<_ForwardIterator1>::value_type __v1;
1390    typedef typename iterator_traits<_ForwardIterator2>::value_type __v2;
1391    return _VSTD::is_permutation(__first1, __last1, __first2, __equal_to<__v1, __v2>());
1392}
1393
1394#if _LIBCPP_STD_VER > 11
1395template<class _BinaryPredicate, class _ForwardIterator1, class _ForwardIterator2>
1396_LIBCPP_CONSTEXPR_AFTER_CXX17 bool
1397__is_permutation(_ForwardIterator1 __first1, _ForwardIterator1 __last1,
1398                 _ForwardIterator2 __first2, _ForwardIterator2 __last2,
1399                 _BinaryPredicate __pred,
1400                 forward_iterator_tag, forward_iterator_tag )
1401{
1402//  shorten sequences as much as possible by lopping of any equal prefix
1403    for (; __first1 != __last1 && __first2 != __last2; ++__first1, (void) ++__first2)
1404        if (!__pred(*__first1, *__first2))
1405            break;
1406    if (__first1 == __last1)
1407        return __first2 == __last2;
1408    else if (__first2 == __last2)
1409        return false;
1410
1411    typedef typename iterator_traits<_ForwardIterator1>::difference_type _D1;
1412    _D1 __l1 = _VSTD::distance(__first1, __last1);
1413
1414    typedef typename iterator_traits<_ForwardIterator2>::difference_type _D2;
1415    _D2 __l2 = _VSTD::distance(__first2, __last2);
1416    if (__l1 != __l2)
1417        return false;
1418
1419    // For each element in [f1, l1) see if there are the same number of
1420    //    equal elements in [f2, l2)
1421    for (_ForwardIterator1 __i = __first1; __i != __last1; ++__i)
1422    {
1423    //  Have we already counted the number of *__i in [f1, l1)?
1424        _ForwardIterator1 __match = __first1;
1425        for (; __match != __i; ++__match)
1426            if (__pred(*__match, *__i))
1427                break;
1428        if (__match == __i) {
1429            // Count number of *__i in [f2, l2)
1430            _D1 __c2 = 0;
1431            for (_ForwardIterator2 __j = __first2; __j != __last2; ++__j)
1432                if (__pred(*__i, *__j))
1433                    ++__c2;
1434            if (__c2 == 0)
1435                return false;
1436            // Count number of *__i in [__i, l1) (we can start with 1)
1437            _D1 __c1 = 1;
1438            for (_ForwardIterator1 __j = _VSTD::next(__i); __j != __last1; ++__j)
1439                if (__pred(*__i, *__j))
1440                    ++__c1;
1441            if (__c1 != __c2)
1442                return false;
1443        }
1444    }
1445    return true;
1446}
1447
1448template<class _BinaryPredicate, class _RandomAccessIterator1, class _RandomAccessIterator2>
1449_LIBCPP_CONSTEXPR_AFTER_CXX17 bool
1450__is_permutation(_RandomAccessIterator1 __first1, _RandomAccessIterator2 __last1,
1451               _RandomAccessIterator1 __first2, _RandomAccessIterator2 __last2,
1452               _BinaryPredicate __pred,
1453               random_access_iterator_tag, random_access_iterator_tag )
1454{
1455    if ( _VSTD::distance(__first1, __last1) != _VSTD::distance(__first2, __last2))
1456        return false;
1457    return _VSTD::is_permutation<_RandomAccessIterator1, _RandomAccessIterator2,
1458                                 typename add_lvalue_reference<_BinaryPredicate>::type>
1459                                (__first1, __last1, __first2, __pred );
1460}
1461
1462template<class _ForwardIterator1, class _ForwardIterator2, class _BinaryPredicate>
1463_LIBCPP_NODISCARD_EXT inline
1464_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
1465bool
1466is_permutation(_ForwardIterator1 __first1, _ForwardIterator1 __last1,
1467               _ForwardIterator2 __first2, _ForwardIterator2 __last2,
1468               _BinaryPredicate __pred )
1469{
1470    return _VSTD::__is_permutation<typename add_lvalue_reference<_BinaryPredicate>::type>
1471       (__first1, __last1, __first2, __last2, __pred,
1472        typename iterator_traits<_ForwardIterator1>::iterator_category(),
1473        typename iterator_traits<_ForwardIterator2>::iterator_category());
1474}
1475
1476template<class _ForwardIterator1, class _ForwardIterator2>
1477_LIBCPP_NODISCARD_EXT inline
1478_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
1479bool
1480is_permutation(_ForwardIterator1 __first1, _ForwardIterator1 __last1,
1481               _ForwardIterator2 __first2, _ForwardIterator2 __last2)
1482{
1483    typedef typename iterator_traits<_ForwardIterator1>::value_type __v1;
1484    typedef typename iterator_traits<_ForwardIterator2>::value_type __v2;
1485    return _VSTD::__is_permutation(__first1, __last1, __first2, __last2,
1486        __equal_to<__v1, __v2>(),
1487        typename iterator_traits<_ForwardIterator1>::iterator_category(),
1488        typename iterator_traits<_ForwardIterator2>::iterator_category());
1489}
1490#endif
1491
1492// search
1493// __search is in <functional>
1494
1495template <class _ForwardIterator1, class _ForwardIterator2, class _BinaryPredicate>
1496_LIBCPP_NODISCARD_EXT inline
1497_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
1498_ForwardIterator1
1499search(_ForwardIterator1 __first1, _ForwardIterator1 __last1,
1500       _ForwardIterator2 __first2, _ForwardIterator2 __last2, _BinaryPredicate __pred)
1501{
1502    return _VSTD::__search<typename add_lvalue_reference<_BinaryPredicate>::type>
1503                         (__first1, __last1, __first2, __last2, __pred,
1504                          typename iterator_traits<_ForwardIterator1>::iterator_category(),
1505                          typename iterator_traits<_ForwardIterator2>::iterator_category())
1506            .first;
1507}
1508
1509template <class _ForwardIterator1, class _ForwardIterator2>
1510_LIBCPP_NODISCARD_EXT inline
1511_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
1512_ForwardIterator1
1513search(_ForwardIterator1 __first1, _ForwardIterator1 __last1,
1514       _ForwardIterator2 __first2, _ForwardIterator2 __last2)
1515{
1516    typedef typename iterator_traits<_ForwardIterator1>::value_type __v1;
1517    typedef typename iterator_traits<_ForwardIterator2>::value_type __v2;
1518    return _VSTD::search(__first1, __last1, __first2, __last2, __equal_to<__v1, __v2>());
1519}
1520
1521
1522#if _LIBCPP_STD_VER > 14
1523template <class _ForwardIterator, class _Searcher>
1524_LIBCPP_NODISCARD_EXT _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
1525_ForwardIterator search(_ForwardIterator __f, _ForwardIterator __l, const _Searcher &__s)
1526{ return __s(__f, __l).first; }
1527#endif
1528
1529// search_n
1530
1531template <class _BinaryPredicate, class _ForwardIterator, class _Size, class _Tp>
1532_LIBCPP_CONSTEXPR_AFTER_CXX17 _ForwardIterator
1533__search_n(_ForwardIterator __first, _ForwardIterator __last,
1534           _Size __count, const _Tp& __value_, _BinaryPredicate __pred, forward_iterator_tag)
1535{
1536    if (__count <= 0)
1537        return __first;
1538    while (true)
1539    {
1540        // Find first element in sequence that matchs __value_, with a mininum of loop checks
1541        while (true)
1542        {
1543            if (__first == __last)  // return __last if no element matches __value_
1544                return __last;
1545            if (__pred(*__first, __value_))
1546                break;
1547            ++__first;
1548        }
1549        // *__first matches __value_, now match elements after here
1550        _ForwardIterator __m = __first;
1551        _Size __c(0);
1552        while (true)
1553        {
1554            if (++__c == __count)  // If pattern exhausted, __first is the answer (works for 1 element pattern)
1555                return __first;
1556            if (++__m == __last)  // Otherwise if source exhaused, pattern not found
1557                return __last;
1558            if (!__pred(*__m, __value_))  // if there is a mismatch, restart with a new __first
1559            {
1560                __first = __m;
1561                ++__first;
1562                break;
1563            }  // else there is a match, check next elements
1564        }
1565    }
1566}
1567
1568template <class _BinaryPredicate, class _RandomAccessIterator, class _Size, class _Tp>
1569_LIBCPP_CONSTEXPR_AFTER_CXX17 _RandomAccessIterator
1570__search_n(_RandomAccessIterator __first, _RandomAccessIterator __last,
1571           _Size __count, const _Tp& __value_, _BinaryPredicate __pred, random_access_iterator_tag)
1572{
1573    if (__count <= 0)
1574        return __first;
1575    _Size __len = static_cast<_Size>(__last - __first);
1576    if (__len < __count)
1577        return __last;
1578    const _RandomAccessIterator __s = __last - (__count - 1);  // Start of pattern match can't go beyond here
1579    while (true)
1580    {
1581        // Find first element in sequence that matchs __value_, with a mininum of loop checks
1582        while (true)
1583        {
1584            if (__first >= __s)  // return __last if no element matches __value_
1585                return __last;
1586            if (__pred(*__first, __value_))
1587                break;
1588            ++__first;
1589        }
1590        // *__first matches __value_, now match elements after here
1591        _RandomAccessIterator __m = __first;
1592        _Size __c(0);
1593        while (true)
1594        {
1595            if (++__c == __count)  // If pattern exhausted, __first is the answer (works for 1 element pattern)
1596                return __first;
1597             ++__m;          // no need to check range on __m because __s guarantees we have enough source
1598            if (!__pred(*__m, __value_))  // if there is a mismatch, restart with a new __first
1599            {
1600                __first = __m;
1601                ++__first;
1602                break;
1603            }  // else there is a match, check next elements
1604        }
1605    }
1606}
1607
1608template <class _ForwardIterator, class _Size, class _Tp, class _BinaryPredicate>
1609_LIBCPP_NODISCARD_EXT inline
1610_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
1611_ForwardIterator
1612search_n(_ForwardIterator __first, _ForwardIterator __last,
1613         _Size __count, const _Tp& __value_, _BinaryPredicate __pred)
1614{
1615    return _VSTD::__search_n<typename add_lvalue_reference<_BinaryPredicate>::type>
1616           (__first, __last, __convert_to_integral(__count), __value_, __pred,
1617           typename iterator_traits<_ForwardIterator>::iterator_category());
1618}
1619
1620template <class _ForwardIterator, class _Size, class _Tp>
1621_LIBCPP_NODISCARD_EXT inline
1622_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
1623_ForwardIterator
1624search_n(_ForwardIterator __first, _ForwardIterator __last, _Size __count, const _Tp& __value_)
1625{
1626    typedef typename iterator_traits<_ForwardIterator>::value_type __v;
1627    return _VSTD::search_n(__first, __last, __convert_to_integral(__count),
1628                           __value_, __equal_to<__v, _Tp>());
1629}
1630
1631// copy
1632template <class _Iter>
1633inline _LIBCPP_INLINE_VISIBILITY
1634_Iter
1635__unwrap_iter(_Iter __i)
1636{
1637    return __i;
1638}
1639
1640template <class _Tp>
1641inline _LIBCPP_INLINE_VISIBILITY
1642typename enable_if
1643<
1644    is_trivially_copy_assignable<_Tp>::value,
1645    _Tp*
1646>::type
1647__unwrap_iter(move_iterator<_Tp*> __i)
1648{
1649    return __i.base();
1650}
1651
1652#if _LIBCPP_DEBUG_LEVEL < 2
1653
1654template <class _Tp>
1655inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_IF_NODEBUG
1656typename enable_if
1657<
1658    is_trivially_copy_assignable<_Tp>::value,
1659    _Tp*
1660>::type
1661__unwrap_iter(__wrap_iter<_Tp*> __i)
1662{
1663    return __i.base();
1664}
1665
1666template <class _Tp>
1667inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_IF_NODEBUG
1668typename enable_if
1669<
1670    is_trivially_copy_assignable<_Tp>::value,
1671    const _Tp*
1672>::type
1673__unwrap_iter(__wrap_iter<const _Tp*> __i)
1674{
1675    return __i.base();
1676}
1677
1678#else
1679
1680template <class _Tp>
1681inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_IF_NODEBUG
1682typename enable_if
1683<
1684    is_trivially_copy_assignable<_Tp>::value,
1685    __wrap_iter<_Tp*>
1686>::type
1687__unwrap_iter(__wrap_iter<_Tp*> __i)
1688{
1689    return __i;
1690}
1691
1692#endif  // _LIBCPP_DEBUG_LEVEL < 2
1693
1694template <class _InputIterator, class _OutputIterator>
1695inline _LIBCPP_INLINE_VISIBILITY
1696_OutputIterator
1697__copy(_InputIterator __first, _InputIterator __last, _OutputIterator __result)
1698{
1699    for (; __first != __last; ++__first, (void) ++__result)
1700        *__result = *__first;
1701    return __result;
1702}
1703
1704template <class _Tp, class _Up>
1705inline _LIBCPP_INLINE_VISIBILITY
1706typename enable_if
1707<
1708    is_same<typename remove_const<_Tp>::type, _Up>::value &&
1709    is_trivially_copy_assignable<_Up>::value,
1710    _Up*
1711>::type
1712__copy(_Tp* __first, _Tp* __last, _Up* __result)
1713{
1714    const size_t __n = static_cast<size_t>(__last - __first);
1715    if (__n > 0)
1716        _VSTD::memmove(__result, __first, __n * sizeof(_Up));
1717    return __result + __n;
1718}
1719
1720template <class _InputIterator, class _OutputIterator>
1721inline _LIBCPP_INLINE_VISIBILITY
1722_OutputIterator
1723copy(_InputIterator __first, _InputIterator __last, _OutputIterator __result)
1724{
1725    return _VSTD::__copy(__unwrap_iter(__first), __unwrap_iter(__last), __unwrap_iter(__result));
1726}
1727
1728// copy_backward
1729
1730template <class _BidirectionalIterator, class _OutputIterator>
1731inline _LIBCPP_INLINE_VISIBILITY
1732_OutputIterator
1733__copy_backward(_BidirectionalIterator __first, _BidirectionalIterator __last, _OutputIterator __result)
1734{
1735    while (__first != __last)
1736        *--__result = *--__last;
1737    return __result;
1738}
1739
1740template <class _Tp, class _Up>
1741inline _LIBCPP_INLINE_VISIBILITY
1742typename enable_if
1743<
1744    is_same<typename remove_const<_Tp>::type, _Up>::value &&
1745    is_trivially_copy_assignable<_Up>::value,
1746    _Up*
1747>::type
1748__copy_backward(_Tp* __first, _Tp* __last, _Up* __result)
1749{
1750    const size_t __n = static_cast<size_t>(__last - __first);
1751    if (__n > 0)
1752    {
1753        __result -= __n;
1754        _VSTD::memmove(__result, __first, __n * sizeof(_Up));
1755    }
1756    return __result;
1757}
1758
1759template <class _BidirectionalIterator1, class _BidirectionalIterator2>
1760inline _LIBCPP_INLINE_VISIBILITY
1761_BidirectionalIterator2
1762copy_backward(_BidirectionalIterator1 __first, _BidirectionalIterator1 __last,
1763              _BidirectionalIterator2 __result)
1764{
1765    return _VSTD::__copy_backward(__unwrap_iter(__first),
1766                                  __unwrap_iter(__last),
1767                                  __unwrap_iter(__result));
1768}
1769
1770// copy_if
1771
1772template<class _InputIterator, class _OutputIterator, class _Predicate>
1773inline _LIBCPP_INLINE_VISIBILITY
1774_OutputIterator
1775copy_if(_InputIterator __first, _InputIterator __last,
1776        _OutputIterator __result, _Predicate __pred)
1777{
1778    for (; __first != __last; ++__first)
1779    {
1780        if (__pred(*__first))
1781        {
1782            *__result = *__first;
1783            ++__result;
1784        }
1785    }
1786    return __result;
1787}
1788
1789// copy_n
1790
1791template<class _InputIterator, class _Size, class _OutputIterator>
1792inline _LIBCPP_INLINE_VISIBILITY
1793typename enable_if
1794<
1795    __is_input_iterator<_InputIterator>::value &&
1796   !__is_random_access_iterator<_InputIterator>::value,
1797    _OutputIterator
1798>::type
1799copy_n(_InputIterator __first, _Size __orig_n, _OutputIterator __result)
1800{
1801    typedef decltype(__convert_to_integral(__orig_n)) _IntegralSize;
1802    _IntegralSize __n = __orig_n;
1803    if (__n > 0)
1804    {
1805        *__result = *__first;
1806        ++__result;
1807        for (--__n; __n > 0; --__n)
1808        {
1809            ++__first;
1810            *__result = *__first;
1811            ++__result;
1812        }
1813    }
1814    return __result;
1815}
1816
1817template<class _InputIterator, class _Size, class _OutputIterator>
1818inline _LIBCPP_INLINE_VISIBILITY
1819typename enable_if
1820<
1821    __is_random_access_iterator<_InputIterator>::value,
1822    _OutputIterator
1823>::type
1824copy_n(_InputIterator __first, _Size __orig_n, _OutputIterator __result)
1825{
1826    typedef decltype(__convert_to_integral(__orig_n)) _IntegralSize;
1827    _IntegralSize __n = __orig_n;
1828    return _VSTD::copy(__first, __first + __n, __result);
1829}
1830
1831// move
1832
1833template <class _InputIterator, class _OutputIterator>
1834inline _LIBCPP_INLINE_VISIBILITY
1835_OutputIterator
1836__move(_InputIterator __first, _InputIterator __last, _OutputIterator __result)
1837{
1838    for (; __first != __last; ++__first, (void) ++__result)
1839        *__result = _VSTD::move(*__first);
1840    return __result;
1841}
1842
1843template <class _Tp, class _Up>
1844inline _LIBCPP_INLINE_VISIBILITY
1845typename enable_if
1846<
1847    is_same<typename remove_const<_Tp>::type, _Up>::value &&
1848    is_trivially_copy_assignable<_Up>::value,
1849    _Up*
1850>::type
1851__move(_Tp* __first, _Tp* __last, _Up* __result)
1852{
1853    const size_t __n = static_cast<size_t>(__last - __first);
1854    if (__n > 0)
1855        _VSTD::memmove(__result, __first, __n * sizeof(_Up));
1856    return __result + __n;
1857}
1858
1859template <class _InputIterator, class _OutputIterator>
1860inline _LIBCPP_INLINE_VISIBILITY
1861_OutputIterator
1862move(_InputIterator __first, _InputIterator __last, _OutputIterator __result)
1863{
1864    return _VSTD::__move(__unwrap_iter(__first), __unwrap_iter(__last), __unwrap_iter(__result));
1865}
1866
1867// move_backward
1868
1869template <class _InputIterator, class _OutputIterator>
1870inline _LIBCPP_INLINE_VISIBILITY
1871_OutputIterator
1872__move_backward(_InputIterator __first, _InputIterator __last, _OutputIterator __result)
1873{
1874    while (__first != __last)
1875        *--__result = _VSTD::move(*--__last);
1876    return __result;
1877}
1878
1879template <class _Tp, class _Up>
1880inline _LIBCPP_INLINE_VISIBILITY
1881typename enable_if
1882<
1883    is_same<typename remove_const<_Tp>::type, _Up>::value &&
1884    is_trivially_copy_assignable<_Up>::value,
1885    _Up*
1886>::type
1887__move_backward(_Tp* __first, _Tp* __last, _Up* __result)
1888{
1889    const size_t __n = static_cast<size_t>(__last - __first);
1890    if (__n > 0)
1891    {
1892        __result -= __n;
1893        _VSTD::memmove(__result, __first, __n * sizeof(_Up));
1894    }
1895    return __result;
1896}
1897
1898template <class _BidirectionalIterator1, class _BidirectionalIterator2>
1899inline _LIBCPP_INLINE_VISIBILITY
1900_BidirectionalIterator2
1901move_backward(_BidirectionalIterator1 __first, _BidirectionalIterator1 __last,
1902              _BidirectionalIterator2 __result)
1903{
1904    return _VSTD::__move_backward(__unwrap_iter(__first), __unwrap_iter(__last), __unwrap_iter(__result));
1905}
1906
1907// iter_swap
1908
1909// moved to <type_traits> for better swap / noexcept support
1910
1911// transform
1912
1913template <class _InputIterator, class _OutputIterator, class _UnaryOperation>
1914inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
1915_OutputIterator
1916transform(_InputIterator __first, _InputIterator __last, _OutputIterator __result, _UnaryOperation __op)
1917{
1918    for (; __first != __last; ++__first, (void) ++__result)
1919        *__result = __op(*__first);
1920    return __result;
1921}
1922
1923template <class _InputIterator1, class _InputIterator2, class _OutputIterator, class _BinaryOperation>
1924inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
1925_OutputIterator
1926transform(_InputIterator1 __first1, _InputIterator1 __last1, _InputIterator2 __first2,
1927          _OutputIterator __result, _BinaryOperation __binary_op)
1928{
1929    for (; __first1 != __last1; ++__first1, (void) ++__first2, ++__result)
1930        *__result = __binary_op(*__first1, *__first2);
1931    return __result;
1932}
1933
1934// replace
1935
1936template <class _ForwardIterator, class _Tp>
1937inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
1938void
1939replace(_ForwardIterator __first, _ForwardIterator __last, const _Tp& __old_value, const _Tp& __new_value)
1940{
1941    for (; __first != __last; ++__first)
1942        if (*__first == __old_value)
1943            *__first = __new_value;
1944}
1945
1946// replace_if
1947
1948template <class _ForwardIterator, class _Predicate, class _Tp>
1949inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
1950void
1951replace_if(_ForwardIterator __first, _ForwardIterator __last, _Predicate __pred, const _Tp& __new_value)
1952{
1953    for (; __first != __last; ++__first)
1954        if (__pred(*__first))
1955            *__first = __new_value;
1956}
1957
1958// replace_copy
1959
1960template <class _InputIterator, class _OutputIterator, class _Tp>
1961inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
1962_OutputIterator
1963replace_copy(_InputIterator __first, _InputIterator __last, _OutputIterator __result,
1964             const _Tp& __old_value, const _Tp& __new_value)
1965{
1966    for (; __first != __last; ++__first, (void) ++__result)
1967        if (*__first == __old_value)
1968            *__result = __new_value;
1969        else
1970            *__result = *__first;
1971    return __result;
1972}
1973
1974// replace_copy_if
1975
1976template <class _InputIterator, class _OutputIterator, class _Predicate, class _Tp>
1977inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
1978_OutputIterator
1979replace_copy_if(_InputIterator __first, _InputIterator __last, _OutputIterator __result,
1980                _Predicate __pred, const _Tp& __new_value)
1981{
1982    for (; __first != __last; ++__first, (void) ++__result)
1983        if (__pred(*__first))
1984            *__result = __new_value;
1985        else
1986            *__result = *__first;
1987    return __result;
1988}
1989
1990// fill_n
1991
1992template <class _OutputIterator, class _Size, class _Tp>
1993inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
1994_OutputIterator
1995__fill_n(_OutputIterator __first, _Size __n, const _Tp& __value_)
1996{
1997    for (; __n > 0; ++__first, (void) --__n)
1998        *__first = __value_;
1999    return __first;
2000}
2001
2002template <class _OutputIterator, class _Size, class _Tp>
2003inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
2004_OutputIterator
2005fill_n(_OutputIterator __first, _Size __n, const _Tp& __value_)
2006{
2007   return _VSTD::__fill_n(__first, __convert_to_integral(__n), __value_);
2008}
2009
2010// fill
2011
2012template <class _ForwardIterator, class _Tp>
2013inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
2014void
2015__fill(_ForwardIterator __first, _ForwardIterator __last, const _Tp& __value_, forward_iterator_tag)
2016{
2017    for (; __first != __last; ++__first)
2018        *__first = __value_;
2019}
2020
2021template <class _RandomAccessIterator, class _Tp>
2022inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
2023void
2024__fill(_RandomAccessIterator __first, _RandomAccessIterator __last, const _Tp& __value_, random_access_iterator_tag)
2025{
2026    _VSTD::fill_n(__first, __last - __first, __value_);
2027}
2028
2029template <class _ForwardIterator, class _Tp>
2030inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
2031void
2032fill(_ForwardIterator __first, _ForwardIterator __last, const _Tp& __value_)
2033{
2034    _VSTD::__fill(__first, __last, __value_, typename iterator_traits<_ForwardIterator>::iterator_category());
2035}
2036
2037// generate
2038
2039template <class _ForwardIterator, class _Generator>
2040inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
2041void
2042generate(_ForwardIterator __first, _ForwardIterator __last, _Generator __gen)
2043{
2044    for (; __first != __last; ++__first)
2045        *__first = __gen();
2046}
2047
2048// generate_n
2049
2050template <class _OutputIterator, class _Size, class _Generator>
2051inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
2052_OutputIterator
2053generate_n(_OutputIterator __first, _Size __orig_n, _Generator __gen)
2054{
2055    typedef decltype(__convert_to_integral(__orig_n)) _IntegralSize;
2056    _IntegralSize __n = __orig_n;
2057    for (; __n > 0; ++__first, (void) --__n)
2058        *__first = __gen();
2059    return __first;
2060}
2061
2062// remove
2063
2064template <class _ForwardIterator, class _Tp>
2065_LIBCPP_NODISCARD_EXT _LIBCPP_CONSTEXPR_AFTER_CXX17 _ForwardIterator
2066remove(_ForwardIterator __first, _ForwardIterator __last, const _Tp& __value_)
2067{
2068    __first = _VSTD::find(__first, __last, __value_);
2069    if (__first != __last)
2070    {
2071        _ForwardIterator __i = __first;
2072        while (++__i != __last)
2073        {
2074            if (!(*__i == __value_))
2075            {
2076                *__first = _VSTD::move(*__i);
2077                ++__first;
2078            }
2079        }
2080    }
2081    return __first;
2082}
2083
2084// remove_if
2085
2086template <class _ForwardIterator, class _Predicate>
2087_LIBCPP_NODISCARD_EXT _LIBCPP_CONSTEXPR_AFTER_CXX17 _ForwardIterator
2088remove_if(_ForwardIterator __first, _ForwardIterator __last, _Predicate __pred)
2089{
2090    __first = _VSTD::find_if<_ForwardIterator, typename add_lvalue_reference<_Predicate>::type>
2091                           (__first, __last, __pred);
2092    if (__first != __last)
2093    {
2094        _ForwardIterator __i = __first;
2095        while (++__i != __last)
2096        {
2097            if (!__pred(*__i))
2098            {
2099                *__first = _VSTD::move(*__i);
2100                ++__first;
2101            }
2102        }
2103    }
2104    return __first;
2105}
2106
2107// remove_copy
2108
2109template <class _InputIterator, class _OutputIterator, class _Tp>
2110inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
2111_OutputIterator
2112remove_copy(_InputIterator __first, _InputIterator __last, _OutputIterator __result, const _Tp& __value_)
2113{
2114    for (; __first != __last; ++__first)
2115    {
2116        if (!(*__first == __value_))
2117        {
2118            *__result = *__first;
2119            ++__result;
2120        }
2121    }
2122    return __result;
2123}
2124
2125// remove_copy_if
2126
2127template <class _InputIterator, class _OutputIterator, class _Predicate>
2128inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
2129_OutputIterator
2130remove_copy_if(_InputIterator __first, _InputIterator __last, _OutputIterator __result, _Predicate __pred)
2131{
2132    for (; __first != __last; ++__first)
2133    {
2134        if (!__pred(*__first))
2135        {
2136            *__result = *__first;
2137            ++__result;
2138        }
2139    }
2140    return __result;
2141}
2142
2143// unique
2144
2145template <class _ForwardIterator, class _BinaryPredicate>
2146_LIBCPP_NODISCARD_EXT _LIBCPP_CONSTEXPR_AFTER_CXX17 _ForwardIterator
2147unique(_ForwardIterator __first, _ForwardIterator __last, _BinaryPredicate __pred)
2148{
2149    __first = _VSTD::adjacent_find<_ForwardIterator, typename add_lvalue_reference<_BinaryPredicate>::type>
2150                                 (__first, __last, __pred);
2151    if (__first != __last)
2152    {
2153        // ...  a  a  ?  ...
2154        //      f     i
2155        _ForwardIterator __i = __first;
2156        for (++__i; ++__i != __last;)
2157            if (!__pred(*__first, *__i))
2158                *++__first = _VSTD::move(*__i);
2159        ++__first;
2160    }
2161    return __first;
2162}
2163
2164template <class _ForwardIterator>
2165_LIBCPP_NODISCARD_EXT inline
2166_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
2167_ForwardIterator
2168unique(_ForwardIterator __first, _ForwardIterator __last)
2169{
2170    typedef typename iterator_traits<_ForwardIterator>::value_type __v;
2171    return _VSTD::unique(__first, __last, __equal_to<__v>());
2172}
2173
2174// unique_copy
2175
2176template <class _BinaryPredicate, class _InputIterator, class _OutputIterator>
2177_LIBCPP_CONSTEXPR_AFTER_CXX17 _OutputIterator
2178__unique_copy(_InputIterator __first, _InputIterator __last, _OutputIterator __result, _BinaryPredicate __pred,
2179              input_iterator_tag, output_iterator_tag)
2180{
2181    if (__first != __last)
2182    {
2183        typename iterator_traits<_InputIterator>::value_type __t(*__first);
2184        *__result = __t;
2185        ++__result;
2186        while (++__first != __last)
2187        {
2188            if (!__pred(__t, *__first))
2189            {
2190                __t = *__first;
2191                *__result = __t;
2192                ++__result;
2193            }
2194        }
2195    }
2196    return __result;
2197}
2198
2199template <class _BinaryPredicate, class _ForwardIterator, class _OutputIterator>
2200_LIBCPP_CONSTEXPR_AFTER_CXX17 _OutputIterator
2201__unique_copy(_ForwardIterator __first, _ForwardIterator __last, _OutputIterator __result, _BinaryPredicate __pred,
2202              forward_iterator_tag, output_iterator_tag)
2203{
2204    if (__first != __last)
2205    {
2206        _ForwardIterator __i = __first;
2207        *__result = *__i;
2208        ++__result;
2209        while (++__first != __last)
2210        {
2211            if (!__pred(*__i, *__first))
2212            {
2213                *__result = *__first;
2214                ++__result;
2215                __i = __first;
2216            }
2217        }
2218    }
2219    return __result;
2220}
2221
2222template <class _BinaryPredicate, class _InputIterator, class _ForwardIterator>
2223_LIBCPP_CONSTEXPR_AFTER_CXX17 _ForwardIterator
2224__unique_copy(_InputIterator __first, _InputIterator __last, _ForwardIterator __result, _BinaryPredicate __pred,
2225              input_iterator_tag, forward_iterator_tag)
2226{
2227    if (__first != __last)
2228    {
2229        *__result = *__first;
2230        while (++__first != __last)
2231            if (!__pred(*__result, *__first))
2232                *++__result = *__first;
2233        ++__result;
2234    }
2235    return __result;
2236}
2237
2238template <class _InputIterator, class _OutputIterator, class _BinaryPredicate>
2239inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
2240_OutputIterator
2241unique_copy(_InputIterator __first, _InputIterator __last, _OutputIterator __result, _BinaryPredicate __pred)
2242{
2243    return _VSTD::__unique_copy<typename add_lvalue_reference<_BinaryPredicate>::type>
2244                              (__first, __last, __result, __pred,
2245                               typename iterator_traits<_InputIterator>::iterator_category(),
2246                               typename iterator_traits<_OutputIterator>::iterator_category());
2247}
2248
2249template <class _InputIterator, class _OutputIterator>
2250inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
2251_OutputIterator
2252unique_copy(_InputIterator __first, _InputIterator __last, _OutputIterator __result)
2253{
2254    typedef typename iterator_traits<_InputIterator>::value_type __v;
2255    return _VSTD::unique_copy(__first, __last, __result, __equal_to<__v>());
2256}
2257
2258// reverse
2259
2260template <class _BidirectionalIterator>
2261inline _LIBCPP_INLINE_VISIBILITY
2262void
2263__reverse(_BidirectionalIterator __first, _BidirectionalIterator __last, bidirectional_iterator_tag)
2264{
2265    while (__first != __last)
2266    {
2267        if (__first == --__last)
2268            break;
2269        _VSTD::iter_swap(__first, __last);
2270        ++__first;
2271    }
2272}
2273
2274template <class _RandomAccessIterator>
2275inline _LIBCPP_INLINE_VISIBILITY
2276void
2277__reverse(_RandomAccessIterator __first, _RandomAccessIterator __last, random_access_iterator_tag)
2278{
2279    if (__first != __last)
2280        for (; __first < --__last; ++__first)
2281            _VSTD::iter_swap(__first, __last);
2282}
2283
2284template <class _BidirectionalIterator>
2285inline _LIBCPP_INLINE_VISIBILITY
2286void
2287reverse(_BidirectionalIterator __first, _BidirectionalIterator __last)
2288{
2289    _VSTD::__reverse(__first, __last, typename iterator_traits<_BidirectionalIterator>::iterator_category());
2290}
2291
2292// reverse_copy
2293
2294template <class _BidirectionalIterator, class _OutputIterator>
2295inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
2296_OutputIterator
2297reverse_copy(_BidirectionalIterator __first, _BidirectionalIterator __last, _OutputIterator __result)
2298{
2299    for (; __first != __last; ++__result)
2300        *__result = *--__last;
2301    return __result;
2302}
2303
2304// rotate
2305
2306template <class _ForwardIterator>
2307_ForwardIterator
2308__rotate_left(_ForwardIterator __first, _ForwardIterator __last)
2309{
2310    typedef typename iterator_traits<_ForwardIterator>::value_type value_type;
2311    value_type __tmp = _VSTD::move(*__first);
2312    _ForwardIterator __lm1 = _VSTD::move(_VSTD::next(__first), __last, __first);
2313    *__lm1 = _VSTD::move(__tmp);
2314    return __lm1;
2315}
2316
2317template <class _BidirectionalIterator>
2318_BidirectionalIterator
2319__rotate_right(_BidirectionalIterator __first, _BidirectionalIterator __last)
2320{
2321    typedef typename iterator_traits<_BidirectionalIterator>::value_type value_type;
2322    _BidirectionalIterator __lm1 = _VSTD::prev(__last);
2323    value_type __tmp = _VSTD::move(*__lm1);
2324    _BidirectionalIterator __fp1 = _VSTD::move_backward(__first, __lm1, __last);
2325    *__first = _VSTD::move(__tmp);
2326    return __fp1;
2327}
2328
2329template <class _ForwardIterator>
2330_ForwardIterator
2331__rotate_forward(_ForwardIterator __first, _ForwardIterator __middle, _ForwardIterator __last)
2332{
2333    _ForwardIterator __i = __middle;
2334    while (true)
2335    {
2336        swap(*__first, *__i);
2337        ++__first;
2338        if (++__i == __last)
2339            break;
2340        if (__first == __middle)
2341            __middle = __i;
2342    }
2343    _ForwardIterator __r = __first;
2344    if (__first != __middle)
2345    {
2346        __i = __middle;
2347        while (true)
2348        {
2349            swap(*__first, *__i);
2350            ++__first;
2351            if (++__i == __last)
2352            {
2353                if (__first == __middle)
2354                    break;
2355                __i = __middle;
2356            }
2357            else if (__first == __middle)
2358                __middle = __i;
2359        }
2360    }
2361    return __r;
2362}
2363
2364template<typename _Integral>
2365inline _LIBCPP_INLINE_VISIBILITY
2366_Integral
2367__algo_gcd(_Integral __x, _Integral __y)
2368{
2369    do
2370    {
2371        _Integral __t = __x % __y;
2372        __x = __y;
2373        __y = __t;
2374    } while (__y);
2375    return __x;
2376}
2377
2378template<typename _RandomAccessIterator>
2379_RandomAccessIterator
2380__rotate_gcd(_RandomAccessIterator __first, _RandomAccessIterator __middle, _RandomAccessIterator __last)
2381{
2382    typedef typename iterator_traits<_RandomAccessIterator>::difference_type difference_type;
2383    typedef typename iterator_traits<_RandomAccessIterator>::value_type value_type;
2384
2385    const difference_type __m1 = __middle - __first;
2386    const difference_type __m2 = __last - __middle;
2387    if (__m1 == __m2)
2388    {
2389        _VSTD::swap_ranges(__first, __middle, __middle);
2390        return __middle;
2391    }
2392    const difference_type __g = _VSTD::__algo_gcd(__m1, __m2);
2393    for (_RandomAccessIterator __p = __first + __g; __p != __first;)
2394    {
2395        value_type __t(_VSTD::move(*--__p));
2396        _RandomAccessIterator __p1 = __p;
2397        _RandomAccessIterator __p2 = __p1 + __m1;
2398        do
2399        {
2400            *__p1 = _VSTD::move(*__p2);
2401            __p1 = __p2;
2402            const difference_type __d = __last - __p2;
2403            if (__m1 < __d)
2404                __p2 += __m1;
2405            else
2406                __p2 = __first + (__m1 - __d);
2407        } while (__p2 != __p);
2408        *__p1 = _VSTD::move(__t);
2409    }
2410    return __first + __m2;
2411}
2412
2413template <class _ForwardIterator>
2414inline _LIBCPP_INLINE_VISIBILITY
2415_ForwardIterator
2416__rotate(_ForwardIterator __first, _ForwardIterator __middle, _ForwardIterator __last,
2417         _VSTD::forward_iterator_tag)
2418{
2419    typedef typename _VSTD::iterator_traits<_ForwardIterator>::value_type value_type;
2420    if (_VSTD::is_trivially_move_assignable<value_type>::value)
2421    {
2422        if (_VSTD::next(__first) == __middle)
2423            return _VSTD::__rotate_left(__first, __last);
2424    }
2425    return _VSTD::__rotate_forward(__first, __middle, __last);
2426}
2427
2428template <class _BidirectionalIterator>
2429inline _LIBCPP_INLINE_VISIBILITY
2430_BidirectionalIterator
2431__rotate(_BidirectionalIterator __first, _BidirectionalIterator __middle, _BidirectionalIterator __last,
2432         _VSTD::bidirectional_iterator_tag)
2433{
2434    typedef typename _VSTD::iterator_traits<_BidirectionalIterator>::value_type value_type;
2435    if (_VSTD::is_trivially_move_assignable<value_type>::value)
2436    {
2437        if (_VSTD::next(__first) == __middle)
2438            return _VSTD::__rotate_left(__first, __last);
2439        if (_VSTD::next(__middle) == __last)
2440            return _VSTD::__rotate_right(__first, __last);
2441    }
2442    return _VSTD::__rotate_forward(__first, __middle, __last);
2443}
2444
2445template <class _RandomAccessIterator>
2446inline _LIBCPP_INLINE_VISIBILITY
2447_RandomAccessIterator
2448__rotate(_RandomAccessIterator __first, _RandomAccessIterator __middle, _RandomAccessIterator __last,
2449         _VSTD::random_access_iterator_tag)
2450{
2451    typedef typename _VSTD::iterator_traits<_RandomAccessIterator>::value_type value_type;
2452    if (_VSTD::is_trivially_move_assignable<value_type>::value)
2453    {
2454        if (_VSTD::next(__first) == __middle)
2455            return _VSTD::__rotate_left(__first, __last);
2456        if (_VSTD::next(__middle) == __last)
2457            return _VSTD::__rotate_right(__first, __last);
2458        return _VSTD::__rotate_gcd(__first, __middle, __last);
2459    }
2460    return _VSTD::__rotate_forward(__first, __middle, __last);
2461}
2462
2463template <class _ForwardIterator>
2464inline _LIBCPP_INLINE_VISIBILITY
2465_ForwardIterator
2466rotate(_ForwardIterator __first, _ForwardIterator __middle, _ForwardIterator __last)
2467{
2468    if (__first == __middle)
2469        return __last;
2470    if (__middle == __last)
2471        return __first;
2472    return _VSTD::__rotate(__first, __middle, __last,
2473                           typename _VSTD::iterator_traits<_ForwardIterator>::iterator_category());
2474}
2475
2476// rotate_copy
2477
2478template <class _ForwardIterator, class _OutputIterator>
2479inline _LIBCPP_INLINE_VISIBILITY
2480_OutputIterator
2481rotate_copy(_ForwardIterator __first, _ForwardIterator __middle, _ForwardIterator __last, _OutputIterator __result)
2482{
2483    return _VSTD::copy(__first, __middle, _VSTD::copy(__middle, __last, __result));
2484}
2485
2486// min_element
2487
2488template <class _ForwardIterator, class _Compare>
2489_LIBCPP_NODISCARD_EXT inline
2490_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
2491_ForwardIterator
2492min_element(_ForwardIterator __first, _ForwardIterator __last, _Compare __comp)
2493{
2494    static_assert(__is_forward_iterator<_ForwardIterator>::value,
2495        "std::min_element requires a ForwardIterator");
2496    if (__first != __last)
2497    {
2498        _ForwardIterator __i = __first;
2499        while (++__i != __last)
2500            if (__comp(*__i, *__first))
2501                __first = __i;
2502    }
2503    return __first;
2504}
2505
2506template <class _ForwardIterator>
2507_LIBCPP_NODISCARD_EXT inline
2508_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
2509_ForwardIterator
2510min_element(_ForwardIterator __first, _ForwardIterator __last)
2511{
2512    return _VSTD::min_element(__first, __last,
2513              __less<typename iterator_traits<_ForwardIterator>::value_type>());
2514}
2515
2516// min
2517
2518template <class _Tp, class _Compare>
2519_LIBCPP_NODISCARD_EXT inline
2520_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
2521const _Tp&
2522min(const _Tp& __a, const _Tp& __b, _Compare __comp)
2523{
2524    return __comp(__b, __a) ? __b : __a;
2525}
2526
2527template <class _Tp>
2528_LIBCPP_NODISCARD_EXT inline
2529_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
2530const _Tp&
2531min(const _Tp& __a, const _Tp& __b)
2532{
2533    return _VSTD::min(__a, __b, __less<_Tp>());
2534}
2535
2536#ifndef _LIBCPP_CXX03_LANG
2537
2538template<class _Tp, class _Compare>
2539_LIBCPP_NODISCARD_EXT inline
2540_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
2541_Tp
2542min(initializer_list<_Tp> __t, _Compare __comp)
2543{
2544    return *_VSTD::min_element(__t.begin(), __t.end(), __comp);
2545}
2546
2547template<class _Tp>
2548_LIBCPP_NODISCARD_EXT inline
2549_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
2550_Tp
2551min(initializer_list<_Tp> __t)
2552{
2553    return *_VSTD::min_element(__t.begin(), __t.end(), __less<_Tp>());
2554}
2555
2556#endif  // _LIBCPP_CXX03_LANG
2557
2558// max_element
2559
2560template <class _ForwardIterator, class _Compare>
2561_LIBCPP_NODISCARD_EXT inline
2562_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
2563_ForwardIterator
2564max_element(_ForwardIterator __first, _ForwardIterator __last, _Compare __comp)
2565{
2566    static_assert(__is_forward_iterator<_ForwardIterator>::value,
2567        "std::max_element requires a ForwardIterator");
2568    if (__first != __last)
2569    {
2570        _ForwardIterator __i = __first;
2571        while (++__i != __last)
2572            if (__comp(*__first, *__i))
2573                __first = __i;
2574    }
2575    return __first;
2576}
2577
2578
2579template <class _ForwardIterator>
2580_LIBCPP_NODISCARD_EXT inline
2581_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
2582_ForwardIterator
2583max_element(_ForwardIterator __first, _ForwardIterator __last)
2584{
2585    return _VSTD::max_element(__first, __last,
2586              __less<typename iterator_traits<_ForwardIterator>::value_type>());
2587}
2588
2589// max
2590
2591template <class _Tp, class _Compare>
2592_LIBCPP_NODISCARD_EXT inline
2593_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
2594const _Tp&
2595max(const _Tp& __a, const _Tp& __b, _Compare __comp)
2596{
2597    return __comp(__a, __b) ? __b : __a;
2598}
2599
2600template <class _Tp>
2601_LIBCPP_NODISCARD_EXT inline
2602_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
2603const _Tp&
2604max(const _Tp& __a, const _Tp& __b)
2605{
2606    return _VSTD::max(__a, __b, __less<_Tp>());
2607}
2608
2609#ifndef _LIBCPP_CXX03_LANG
2610
2611template<class _Tp, class _Compare>
2612_LIBCPP_NODISCARD_EXT inline
2613_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
2614_Tp
2615max(initializer_list<_Tp> __t, _Compare __comp)
2616{
2617    return *_VSTD::max_element(__t.begin(), __t.end(), __comp);
2618}
2619
2620template<class _Tp>
2621_LIBCPP_NODISCARD_EXT inline
2622_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
2623_Tp
2624max(initializer_list<_Tp> __t)
2625{
2626    return *_VSTD::max_element(__t.begin(), __t.end(), __less<_Tp>());
2627}
2628
2629#endif  // _LIBCPP_CXX03_LANG
2630
2631#if _LIBCPP_STD_VER > 14
2632// clamp
2633template<class _Tp, class _Compare>
2634_LIBCPP_NODISCARD_EXT inline
2635_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
2636const _Tp&
2637clamp(const _Tp& __v, const _Tp& __lo, const _Tp& __hi, _Compare __comp)
2638{
2639    _LIBCPP_ASSERT(!__comp(__hi, __lo), "Bad bounds passed to std::clamp");
2640    return __comp(__v, __lo) ? __lo : __comp(__hi, __v) ? __hi : __v;
2641
2642}
2643
2644template<class _Tp>
2645_LIBCPP_NODISCARD_EXT inline
2646_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
2647const _Tp&
2648clamp(const _Tp& __v, const _Tp& __lo, const _Tp& __hi)
2649{
2650    return _VSTD::clamp(__v, __lo, __hi, __less<_Tp>());
2651}
2652#endif
2653
2654// minmax_element
2655
2656template <class _ForwardIterator, class _Compare>
2657_LIBCPP_NODISCARD_EXT _LIBCPP_CONSTEXPR_AFTER_CXX11
2658std::pair<_ForwardIterator, _ForwardIterator>
2659minmax_element(_ForwardIterator __first, _ForwardIterator __last, _Compare __comp)
2660{
2661  static_assert(__is_forward_iterator<_ForwardIterator>::value,
2662        "std::minmax_element requires a ForwardIterator");
2663  std::pair<_ForwardIterator, _ForwardIterator> __result(__first, __first);
2664  if (__first != __last)
2665  {
2666      if (++__first != __last)
2667      {
2668          if (__comp(*__first, *__result.first))
2669              __result.first = __first;
2670          else
2671              __result.second = __first;
2672          while (++__first != __last)
2673          {
2674              _ForwardIterator __i = __first;
2675              if (++__first == __last)
2676              {
2677                  if (__comp(*__i, *__result.first))
2678                      __result.first = __i;
2679                  else if (!__comp(*__i, *__result.second))
2680                      __result.second = __i;
2681                  break;
2682              }
2683              else
2684              {
2685                  if (__comp(*__first, *__i))
2686                  {
2687                      if (__comp(*__first, *__result.first))
2688                          __result.first = __first;
2689                      if (!__comp(*__i, *__result.second))
2690                          __result.second = __i;
2691                  }
2692                  else
2693                  {
2694                      if (__comp(*__i, *__result.first))
2695                          __result.first = __i;
2696                      if (!__comp(*__first, *__result.second))
2697                          __result.second = __first;
2698                  }
2699              }
2700          }
2701      }
2702  }
2703  return __result;
2704}
2705
2706template <class _ForwardIterator>
2707_LIBCPP_NODISCARD_EXT inline
2708_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
2709std::pair<_ForwardIterator, _ForwardIterator>
2710minmax_element(_ForwardIterator __first, _ForwardIterator __last)
2711{
2712    return _VSTD::minmax_element(__first, __last,
2713              __less<typename iterator_traits<_ForwardIterator>::value_type>());
2714}
2715
2716// minmax
2717
2718template<class _Tp, class _Compare>
2719_LIBCPP_NODISCARD_EXT inline
2720_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
2721pair<const _Tp&, const _Tp&>
2722minmax(const _Tp& __a, const _Tp& __b, _Compare __comp)
2723{
2724    return __comp(__b, __a) ? pair<const _Tp&, const _Tp&>(__b, __a) :
2725                              pair<const _Tp&, const _Tp&>(__a, __b);
2726}
2727
2728template<class _Tp>
2729_LIBCPP_NODISCARD_EXT inline
2730_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
2731pair<const _Tp&, const _Tp&>
2732minmax(const _Tp& __a, const _Tp& __b)
2733{
2734    return _VSTD::minmax(__a, __b, __less<_Tp>());
2735}
2736
2737#ifndef _LIBCPP_CXX03_LANG
2738
2739template<class _Tp, class _Compare>
2740_LIBCPP_NODISCARD_EXT inline
2741_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
2742pair<_Tp, _Tp>
2743minmax(initializer_list<_Tp> __t, _Compare __comp)
2744{
2745    typedef typename initializer_list<_Tp>::const_iterator _Iter;
2746    _Iter __first = __t.begin();
2747    _Iter __last  = __t.end();
2748    std::pair<_Tp, _Tp> __result(*__first, *__first);
2749
2750    ++__first;
2751    if (__t.size() % 2 == 0)
2752    {
2753        if (__comp(*__first,  __result.first))
2754            __result.first  = *__first;
2755        else
2756            __result.second = *__first;
2757        ++__first;
2758    }
2759
2760    while (__first != __last)
2761    {
2762        _Tp __prev = *__first++;
2763        if (__comp(*__first, __prev)) {
2764            if ( __comp(*__first, __result.first)) __result.first  = *__first;
2765            if (!__comp(__prev, __result.second))  __result.second = __prev;
2766            }
2767        else {
2768            if ( __comp(__prev, __result.first))    __result.first  = __prev;
2769            if (!__comp(*__first, __result.second)) __result.second = *__first;
2770            }
2771
2772        __first++;
2773    }
2774    return __result;
2775}
2776
2777template<class _Tp>
2778_LIBCPP_NODISCARD_EXT inline
2779_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
2780pair<_Tp, _Tp>
2781minmax(initializer_list<_Tp> __t)
2782{
2783    return _VSTD::minmax(__t, __less<_Tp>());
2784}
2785
2786#endif  // _LIBCPP_CXX03_LANG
2787
2788// random_shuffle
2789
2790// __independent_bits_engine
2791
2792template <unsigned long long _Xp, size_t _Rp>
2793struct __log2_imp
2794{
2795    static const size_t value = _Xp & ((unsigned long long)(1) << _Rp) ? _Rp
2796                                           : __log2_imp<_Xp, _Rp - 1>::value;
2797};
2798
2799template <unsigned long long _Xp>
2800struct __log2_imp<_Xp, 0>
2801{
2802    static const size_t value = 0;
2803};
2804
2805template <size_t _Rp>
2806struct __log2_imp<0, _Rp>
2807{
2808    static const size_t value = _Rp + 1;
2809};
2810
2811template <class _UIntType, _UIntType _Xp>
2812struct __log2
2813{
2814    static const size_t value = __log2_imp<_Xp,
2815                                         sizeof(_UIntType) * __CHAR_BIT__ - 1>::value;
2816};
2817
2818template<class _Engine, class _UIntType>
2819class __independent_bits_engine
2820{
2821public:
2822    // types
2823    typedef _UIntType result_type;
2824
2825private:
2826    typedef typename _Engine::result_type _Engine_result_type;
2827    typedef typename conditional
2828        <
2829            sizeof(_Engine_result_type) <= sizeof(result_type),
2830                result_type,
2831                _Engine_result_type
2832        >::type _Working_result_type;
2833
2834    _Engine& __e_;
2835    size_t __w_;
2836    size_t __w0_;
2837    size_t __n_;
2838    size_t __n0_;
2839    _Working_result_type __y0_;
2840    _Working_result_type __y1_;
2841    _Engine_result_type __mask0_;
2842    _Engine_result_type __mask1_;
2843
2844#ifdef _LIBCPP_CXX03_LANG
2845    static const _Working_result_type _Rp = _Engine::_Max - _Engine::_Min
2846                                          + _Working_result_type(1);
2847#else
2848    static _LIBCPP_CONSTEXPR const _Working_result_type _Rp = _Engine::max() - _Engine::min()
2849                                                      + _Working_result_type(1);
2850#endif
2851    static _LIBCPP_CONSTEXPR const size_t __m = __log2<_Working_result_type, _Rp>::value;
2852    static _LIBCPP_CONSTEXPR const size_t _WDt = numeric_limits<_Working_result_type>::digits;
2853    static _LIBCPP_CONSTEXPR const size_t _EDt = numeric_limits<_Engine_result_type>::digits;
2854
2855public:
2856    // constructors and seeding functions
2857    __independent_bits_engine(_Engine& __e, size_t __w);
2858
2859    // generating functions
2860    result_type operator()() {return __eval(integral_constant<bool, _Rp != 0>());}
2861
2862private:
2863    result_type __eval(false_type);
2864    result_type __eval(true_type);
2865};
2866
2867template<class _Engine, class _UIntType>
2868__independent_bits_engine<_Engine, _UIntType>
2869    ::__independent_bits_engine(_Engine& __e, size_t __w)
2870        : __e_(__e),
2871          __w_(__w)
2872{
2873    __n_ = __w_ / __m + (__w_ % __m != 0);
2874    __w0_ = __w_ / __n_;
2875    if (_Rp == 0)
2876        __y0_ = _Rp;
2877    else if (__w0_ < _WDt)
2878        __y0_ = (_Rp >> __w0_) << __w0_;
2879    else
2880        __y0_ = 0;
2881    if (_Rp - __y0_ > __y0_ / __n_)
2882    {
2883        ++__n_;
2884        __w0_ = __w_ / __n_;
2885        if (__w0_ < _WDt)
2886            __y0_ = (_Rp >> __w0_) << __w0_;
2887        else
2888            __y0_ = 0;
2889    }
2890    __n0_ = __n_ - __w_ % __n_;
2891    if (__w0_ < _WDt - 1)
2892        __y1_ = (_Rp >> (__w0_ + 1)) << (__w0_ + 1);
2893    else
2894        __y1_ = 0;
2895    __mask0_ = __w0_ > 0 ? _Engine_result_type(~0) >> (_EDt - __w0_) :
2896                          _Engine_result_type(0);
2897    __mask1_ = __w0_ < _EDt - 1 ?
2898                               _Engine_result_type(~0) >> (_EDt - (__w0_ + 1)) :
2899                               _Engine_result_type(~0);
2900}
2901
2902template<class _Engine, class _UIntType>
2903inline
2904_UIntType
2905__independent_bits_engine<_Engine, _UIntType>::__eval(false_type)
2906{
2907    return static_cast<result_type>(__e_() & __mask0_);
2908}
2909
2910template<class _Engine, class _UIntType>
2911_UIntType
2912__independent_bits_engine<_Engine, _UIntType>::__eval(true_type)
2913{
2914    const size_t _WRt = numeric_limits<result_type>::digits;
2915    result_type _Sp = 0;
2916    for (size_t __k = 0; __k < __n0_; ++__k)
2917    {
2918        _Engine_result_type __u;
2919        do
2920        {
2921            __u = __e_() - _Engine::min();
2922        } while (__u >= __y0_);
2923        if (__w0_ < _WRt)
2924            _Sp <<= __w0_;
2925        else
2926            _Sp = 0;
2927        _Sp += __u & __mask0_;
2928    }
2929    for (size_t __k = __n0_; __k < __n_; ++__k)
2930    {
2931        _Engine_result_type __u;
2932        do
2933        {
2934            __u = __e_() - _Engine::min();
2935        } while (__u >= __y1_);
2936        if (__w0_ < _WRt - 1)
2937            _Sp <<= __w0_ + 1;
2938        else
2939            _Sp = 0;
2940        _Sp += __u & __mask1_;
2941    }
2942    return _Sp;
2943}
2944
2945// uniform_int_distribution
2946
2947template<class _IntType = int>
2948class uniform_int_distribution
2949{
2950public:
2951    // types
2952    typedef _IntType result_type;
2953
2954    class param_type
2955    {
2956        result_type __a_;
2957        result_type __b_;
2958    public:
2959        typedef uniform_int_distribution distribution_type;
2960
2961        explicit param_type(result_type __a = 0,
2962                            result_type __b = numeric_limits<result_type>::max())
2963            : __a_(__a), __b_(__b) {}
2964
2965        result_type a() const {return __a_;}
2966        result_type b() const {return __b_;}
2967
2968        friend bool operator==(const param_type& __x, const param_type& __y)
2969            {return __x.__a_ == __y.__a_ && __x.__b_ == __y.__b_;}
2970        friend bool operator!=(const param_type& __x, const param_type& __y)
2971            {return !(__x == __y);}
2972    };
2973
2974private:
2975    param_type __p_;
2976
2977public:
2978    // constructors and reset functions
2979    explicit uniform_int_distribution(result_type __a = 0,
2980                                      result_type __b = numeric_limits<result_type>::max())
2981        : __p_(param_type(__a, __b)) {}
2982    explicit uniform_int_distribution(const param_type& __p) : __p_(__p) {}
2983    void reset() {}
2984
2985    // generating functions
2986    template<class _URNG> result_type operator()(_URNG& __g)
2987        {return (*this)(__g, __p_);}
2988    template<class _URNG> result_type operator()(_URNG& __g, const param_type& __p);
2989
2990    // property functions
2991    result_type a() const {return __p_.a();}
2992    result_type b() const {return __p_.b();}
2993
2994    param_type param() const {return __p_;}
2995    void param(const param_type& __p) {__p_ = __p;}
2996
2997    result_type min() const {return a();}
2998    result_type max() const {return b();}
2999
3000    friend bool operator==(const uniform_int_distribution& __x,
3001                           const uniform_int_distribution& __y)
3002        {return __x.__p_ == __y.__p_;}
3003    friend bool operator!=(const uniform_int_distribution& __x,
3004                           const uniform_int_distribution& __y)
3005            {return !(__x == __y);}
3006};
3007
3008template<class _IntType>
3009template<class _URNG>
3010typename uniform_int_distribution<_IntType>::result_type
3011uniform_int_distribution<_IntType>::operator()(_URNG& __g, const param_type& __p)
3012_LIBCPP_DISABLE_UBSAN_UNSIGNED_INTEGER_CHECK
3013{
3014    typedef typename conditional<sizeof(result_type) <= sizeof(uint32_t),
3015                                            uint32_t, uint64_t>::type _UIntType;
3016    const _UIntType _Rp = _UIntType(__p.b()) - _UIntType(__p.a()) + _UIntType(1);
3017    if (_Rp == 1)
3018        return __p.a();
3019    const size_t _Dt = numeric_limits<_UIntType>::digits;
3020    typedef __independent_bits_engine<_URNG, _UIntType> _Eng;
3021    if (_Rp == 0)
3022        return static_cast<result_type>(_Eng(__g, _Dt)());
3023    size_t __w = _Dt - __clz(_Rp) - 1;
3024    if ((_Rp & (std::numeric_limits<_UIntType>::max() >> (_Dt - __w))) != 0)
3025        ++__w;
3026    _Eng __e(__g, __w);
3027    _UIntType __u;
3028    do
3029    {
3030        __u = __e();
3031    } while (__u >= _Rp);
3032    return static_cast<result_type>(__u + __p.a());
3033}
3034
3035#if _LIBCPP_STD_VER <= 14 || defined(_LIBCPP_ENABLE_CXX17_REMOVED_RANDOM_SHUFFLE) \
3036  || defined(_LIBCPP_BUILDING_LIBRARY)
3037class _LIBCPP_TYPE_VIS __rs_default;
3038
3039_LIBCPP_FUNC_VIS __rs_default __rs_get();
3040
3041class _LIBCPP_TYPE_VIS __rs_default
3042{
3043    static unsigned __c_;
3044
3045    __rs_default();
3046public:
3047    typedef uint_fast32_t result_type;
3048
3049    static const result_type _Min = 0;
3050    static const result_type _Max = 0xFFFFFFFF;
3051
3052    __rs_default(const __rs_default&);
3053    ~__rs_default();
3054
3055    result_type operator()();
3056
3057    static _LIBCPP_CONSTEXPR result_type min() {return _Min;}
3058    static _LIBCPP_CONSTEXPR result_type max() {return _Max;}
3059
3060    friend _LIBCPP_FUNC_VIS __rs_default __rs_get();
3061};
3062
3063_LIBCPP_FUNC_VIS __rs_default __rs_get();
3064
3065template <class _RandomAccessIterator>
3066_LIBCPP_DEPRECATED_IN_CXX14 void
3067random_shuffle(_RandomAccessIterator __first, _RandomAccessIterator __last)
3068{
3069    typedef typename iterator_traits<_RandomAccessIterator>::difference_type difference_type;
3070    typedef uniform_int_distribution<ptrdiff_t> _Dp;
3071    typedef typename _Dp::param_type _Pp;
3072    difference_type __d = __last - __first;
3073    if (__d > 1)
3074    {
3075        _Dp __uid;
3076        __rs_default __g = __rs_get();
3077        for (--__last, (void) --__d; __first < __last; ++__first, (void) --__d)
3078        {
3079            difference_type __i = __uid(__g, _Pp(0, __d));
3080            if (__i != difference_type(0))
3081                swap(*__first, *(__first + __i));
3082        }
3083    }
3084}
3085
3086template <class _RandomAccessIterator, class _RandomNumberGenerator>
3087_LIBCPP_DEPRECATED_IN_CXX14 void
3088random_shuffle(_RandomAccessIterator __first, _RandomAccessIterator __last,
3089#ifndef _LIBCPP_CXX03_LANG
3090               _RandomNumberGenerator&& __rand)
3091#else
3092               _RandomNumberGenerator& __rand)
3093#endif
3094{
3095    typedef typename iterator_traits<_RandomAccessIterator>::difference_type difference_type;
3096    difference_type __d = __last - __first;
3097    if (__d > 1)
3098    {
3099        for (--__last; __first < __last; ++__first, (void) --__d)
3100        {
3101            difference_type __i = __rand(__d);
3102            if (__i != difference_type(0))
3103              swap(*__first, *(__first + __i));
3104        }
3105    }
3106}
3107#endif
3108
3109template <class _PopulationIterator, class _SampleIterator, class _Distance,
3110          class _UniformRandomNumberGenerator>
3111_LIBCPP_INLINE_VISIBILITY
3112_SampleIterator __sample(_PopulationIterator __first,
3113                         _PopulationIterator __last, _SampleIterator __output_iter,
3114                         _Distance __n,
3115                         _UniformRandomNumberGenerator & __g,
3116                         input_iterator_tag) {
3117
3118  _Distance __k = 0;
3119  for (; __first != __last && __k < __n; ++__first, (void)++__k)
3120    __output_iter[__k] = *__first;
3121  _Distance __sz = __k;
3122  for (; __first != __last; ++__first, (void)++__k) {
3123    _Distance __r = _VSTD::uniform_int_distribution<_Distance>(0, __k)(__g);
3124    if (__r < __sz)
3125      __output_iter[__r] = *__first;
3126  }
3127  return __output_iter + _VSTD::min(__n, __k);
3128}
3129
3130template <class _PopulationIterator, class _SampleIterator, class _Distance,
3131          class _UniformRandomNumberGenerator>
3132_LIBCPP_INLINE_VISIBILITY
3133_SampleIterator __sample(_PopulationIterator __first,
3134                         _PopulationIterator __last, _SampleIterator __output_iter,
3135                         _Distance __n,
3136                         _UniformRandomNumberGenerator& __g,
3137                         forward_iterator_tag) {
3138  _Distance __unsampled_sz = _VSTD::distance(__first, __last);
3139  for (__n = _VSTD::min(__n, __unsampled_sz); __n != 0; ++__first) {
3140    _Distance __r =
3141        _VSTD::uniform_int_distribution<_Distance>(0, --__unsampled_sz)(__g);
3142    if (__r < __n) {
3143      *__output_iter++ = *__first;
3144      --__n;
3145    }
3146  }
3147  return __output_iter;
3148}
3149
3150template <class _PopulationIterator, class _SampleIterator, class _Distance,
3151          class _UniformRandomNumberGenerator>
3152_LIBCPP_INLINE_VISIBILITY
3153_SampleIterator __sample(_PopulationIterator __first,
3154                         _PopulationIterator __last, _SampleIterator __output_iter,
3155                         _Distance __n, _UniformRandomNumberGenerator& __g) {
3156  typedef typename iterator_traits<_PopulationIterator>::iterator_category
3157        _PopCategory;
3158  typedef typename iterator_traits<_PopulationIterator>::difference_type
3159        _Difference;
3160  static_assert(__is_forward_iterator<_PopulationIterator>::value ||
3161                __is_random_access_iterator<_SampleIterator>::value,
3162                "SampleIterator must meet the requirements of RandomAccessIterator");
3163  typedef typename common_type<_Distance, _Difference>::type _CommonType;
3164  _LIBCPP_ASSERT(__n >= 0, "N must be a positive number.");
3165  return _VSTD::__sample(
3166      __first, __last, __output_iter, _CommonType(__n),
3167      __g, _PopCategory());
3168}
3169
3170#if _LIBCPP_STD_VER > 14
3171template <class _PopulationIterator, class _SampleIterator, class _Distance,
3172          class _UniformRandomNumberGenerator>
3173inline _LIBCPP_INLINE_VISIBILITY
3174_SampleIterator sample(_PopulationIterator __first,
3175                       _PopulationIterator __last, _SampleIterator __output_iter,
3176                       _Distance __n, _UniformRandomNumberGenerator&& __g) {
3177    return _VSTD::__sample(__first, __last, __output_iter, __n, __g);
3178}
3179#endif // _LIBCPP_STD_VER > 14
3180
3181template<class _RandomAccessIterator, class _UniformRandomNumberGenerator>
3182    void shuffle(_RandomAccessIterator __first, _RandomAccessIterator __last,
3183#ifndef _LIBCPP_CXX03_LANG
3184                 _UniformRandomNumberGenerator&& __g)
3185#else
3186                 _UniformRandomNumberGenerator& __g)
3187#endif
3188{
3189    typedef typename iterator_traits<_RandomAccessIterator>::difference_type difference_type;
3190    typedef uniform_int_distribution<ptrdiff_t> _Dp;
3191    typedef typename _Dp::param_type _Pp;
3192    difference_type __d = __last - __first;
3193    if (__d > 1)
3194    {
3195        _Dp __uid;
3196        for (--__last, --__d; __first < __last; ++__first, --__d)
3197        {
3198            difference_type __i = __uid(__g, _Pp(0, __d));
3199            if (__i != difference_type(0))
3200                swap(*__first, *(__first + __i));
3201        }
3202    }
3203}
3204
3205template <class _InputIterator, class _Predicate>
3206_LIBCPP_NODISCARD_EXT _LIBCPP_CONSTEXPR_AFTER_CXX17 bool
3207is_partitioned(_InputIterator __first, _InputIterator __last, _Predicate __pred)
3208{
3209    for (; __first != __last; ++__first)
3210        if (!__pred(*__first))
3211            break;
3212    if ( __first == __last )
3213        return true;
3214    ++__first;
3215    for (; __first != __last; ++__first)
3216        if (__pred(*__first))
3217            return false;
3218    return true;
3219}
3220
3221// partition
3222
3223template <class _Predicate, class _ForwardIterator>
3224_ForwardIterator
3225__partition(_ForwardIterator __first, _ForwardIterator __last, _Predicate __pred, forward_iterator_tag)
3226{
3227    while (true)
3228    {
3229        if (__first == __last)
3230            return __first;
3231        if (!__pred(*__first))
3232            break;
3233        ++__first;
3234    }
3235    for (_ForwardIterator __p = __first; ++__p != __last;)
3236    {
3237        if (__pred(*__p))
3238        {
3239            swap(*__first, *__p);
3240            ++__first;
3241        }
3242    }
3243    return __first;
3244}
3245
3246template <class _Predicate, class _BidirectionalIterator>
3247_BidirectionalIterator
3248__partition(_BidirectionalIterator __first, _BidirectionalIterator __last, _Predicate __pred,
3249            bidirectional_iterator_tag)
3250{
3251    while (true)
3252    {
3253        while (true)
3254        {
3255            if (__first == __last)
3256                return __first;
3257            if (!__pred(*__first))
3258                break;
3259            ++__first;
3260        }
3261        do
3262        {
3263            if (__first == --__last)
3264                return __first;
3265        } while (!__pred(*__last));
3266        swap(*__first, *__last);
3267        ++__first;
3268    }
3269}
3270
3271template <class _ForwardIterator, class _Predicate>
3272inline _LIBCPP_INLINE_VISIBILITY
3273_ForwardIterator
3274partition(_ForwardIterator __first, _ForwardIterator __last, _Predicate __pred)
3275{
3276    return _VSTD::__partition<typename add_lvalue_reference<_Predicate>::type>
3277                            (__first, __last, __pred, typename iterator_traits<_ForwardIterator>::iterator_category());
3278}
3279
3280// partition_copy
3281
3282template <class _InputIterator, class _OutputIterator1,
3283          class _OutputIterator2, class _Predicate>
3284_LIBCPP_CONSTEXPR_AFTER_CXX17 pair<_OutputIterator1, _OutputIterator2>
3285partition_copy(_InputIterator __first, _InputIterator __last,
3286               _OutputIterator1 __out_true, _OutputIterator2 __out_false,
3287               _Predicate __pred)
3288{
3289    for (; __first != __last; ++__first)
3290    {
3291        if (__pred(*__first))
3292        {
3293            *__out_true = *__first;
3294            ++__out_true;
3295        }
3296        else
3297        {
3298            *__out_false = *__first;
3299            ++__out_false;
3300        }
3301    }
3302    return pair<_OutputIterator1, _OutputIterator2>(__out_true, __out_false);
3303}
3304
3305// partition_point
3306
3307template<class _ForwardIterator, class _Predicate>
3308_LIBCPP_CONSTEXPR_AFTER_CXX17 _ForwardIterator
3309partition_point(_ForwardIterator __first, _ForwardIterator __last, _Predicate __pred)
3310{
3311    typedef typename iterator_traits<_ForwardIterator>::difference_type difference_type;
3312    difference_type __len = _VSTD::distance(__first, __last);
3313    while (__len != 0)
3314    {
3315        difference_type __l2 = _VSTD::__half_positive(__len);
3316        _ForwardIterator __m = __first;
3317        _VSTD::advance(__m, __l2);
3318        if (__pred(*__m))
3319        {
3320            __first = ++__m;
3321            __len -= __l2 + 1;
3322        }
3323        else
3324            __len = __l2;
3325    }
3326    return __first;
3327}
3328
3329// stable_partition
3330
3331template <class _Predicate, class _ForwardIterator, class _Distance, class _Pair>
3332_ForwardIterator
3333__stable_partition(_ForwardIterator __first, _ForwardIterator __last, _Predicate __pred,
3334                   _Distance __len, _Pair __p, forward_iterator_tag __fit)
3335{
3336    // *__first is known to be false
3337    // __len >= 1
3338    if (__len == 1)
3339        return __first;
3340    if (__len == 2)
3341    {
3342        _ForwardIterator __m = __first;
3343        if (__pred(*++__m))
3344        {
3345            swap(*__first, *__m);
3346            return __m;
3347        }
3348        return __first;
3349    }
3350    if (__len <= __p.second)
3351    {   // The buffer is big enough to use
3352        typedef typename iterator_traits<_ForwardIterator>::value_type value_type;
3353        __destruct_n __d(0);
3354        unique_ptr<value_type, __destruct_n&> __h(__p.first, __d);
3355        // Move the falses into the temporary buffer, and the trues to the front of the line
3356        // Update __first to always point to the end of the trues
3357        value_type* __t = __p.first;
3358        ::new(__t) value_type(_VSTD::move(*__first));
3359        __d.__incr((value_type*)0);
3360        ++__t;
3361        _ForwardIterator __i = __first;
3362        while (++__i != __last)
3363        {
3364            if (__pred(*__i))
3365            {
3366                *__first = _VSTD::move(*__i);
3367                ++__first;
3368            }
3369            else
3370            {
3371                ::new(__t) value_type(_VSTD::move(*__i));
3372                __d.__incr((value_type*)0);
3373                ++__t;
3374            }
3375        }
3376        // All trues now at start of range, all falses in buffer
3377        // Move falses back into range, but don't mess up __first which points to first false
3378        __i = __first;
3379        for (value_type* __t2 = __p.first; __t2 < __t; ++__t2, ++__i)
3380            *__i = _VSTD::move(*__t2);
3381        // __h destructs moved-from values out of the temp buffer, but doesn't deallocate buffer
3382        return __first;
3383    }
3384    // Else not enough buffer, do in place
3385    // __len >= 3
3386    _ForwardIterator __m = __first;
3387    _Distance __len2 = __len / 2;  // __len2 >= 2
3388    _VSTD::advance(__m, __len2);
3389    // recurse on [__first, __m), *__first know to be false
3390    // F?????????????????
3391    // f       m         l
3392    typedef typename add_lvalue_reference<_Predicate>::type _PredRef;
3393    _ForwardIterator __first_false = __stable_partition<_PredRef>(__first, __m, __pred, __len2, __p, __fit);
3394    // TTTFFFFF??????????
3395    // f  ff   m         l
3396    // recurse on [__m, __last], except increase __m until *(__m) is false, *__last know to be true
3397    _ForwardIterator __m1 = __m;
3398    _ForwardIterator __second_false = __last;
3399    _Distance __len_half = __len - __len2;
3400    while (__pred(*__m1))
3401    {
3402        if (++__m1 == __last)
3403            goto __second_half_done;
3404        --__len_half;
3405    }
3406    // TTTFFFFFTTTF??????
3407    // f  ff   m  m1     l
3408    __second_false = __stable_partition<_PredRef>(__m1, __last, __pred, __len_half, __p, __fit);
3409__second_half_done:
3410    // TTTFFFFFTTTTTFFFFF
3411    // f  ff   m    sf   l
3412    return _VSTD::rotate(__first_false, __m, __second_false);
3413    // TTTTTTTTFFFFFFFFFF
3414    //         |
3415}
3416
3417struct __return_temporary_buffer
3418{
3419    template <class _Tp>
3420    _LIBCPP_INLINE_VISIBILITY void operator()(_Tp* __p) const {_VSTD::return_temporary_buffer(__p);}
3421};
3422
3423template <class _Predicate, class _ForwardIterator>
3424_ForwardIterator
3425__stable_partition(_ForwardIterator __first, _ForwardIterator __last, _Predicate __pred,
3426                   forward_iterator_tag)
3427{
3428    const unsigned __alloc_limit = 3;  // might want to make this a function of trivial assignment
3429    // Either prove all true and return __first or point to first false
3430    while (true)
3431    {
3432        if (__first == __last)
3433            return __first;
3434        if (!__pred(*__first))
3435            break;
3436        ++__first;
3437    }
3438    // We now have a reduced range [__first, __last)
3439    // *__first is known to be false
3440    typedef typename iterator_traits<_ForwardIterator>::difference_type difference_type;
3441    typedef typename iterator_traits<_ForwardIterator>::value_type value_type;
3442    difference_type __len = _VSTD::distance(__first, __last);
3443    pair<value_type*, ptrdiff_t> __p(0, 0);
3444    unique_ptr<value_type, __return_temporary_buffer> __h;
3445    if (__len >= __alloc_limit)
3446    {
3447        __p = _VSTD::get_temporary_buffer<value_type>(__len);
3448        __h.reset(__p.first);
3449    }
3450    return __stable_partition<typename add_lvalue_reference<_Predicate>::type>
3451                             (__first, __last, __pred, __len, __p, forward_iterator_tag());
3452}
3453
3454template <class _Predicate, class _BidirectionalIterator, class _Distance, class _Pair>
3455_BidirectionalIterator
3456__stable_partition(_BidirectionalIterator __first, _BidirectionalIterator __last, _Predicate __pred,
3457                   _Distance __len, _Pair __p, bidirectional_iterator_tag __bit)
3458{
3459    // *__first is known to be false
3460    // *__last is known to be true
3461    // __len >= 2
3462    if (__len == 2)
3463    {
3464        swap(*__first, *__last);
3465        return __last;
3466    }
3467    if (__len == 3)
3468    {
3469        _BidirectionalIterator __m = __first;
3470        if (__pred(*++__m))
3471        {
3472            swap(*__first, *__m);
3473            swap(*__m, *__last);
3474            return __last;
3475        }
3476        swap(*__m, *__last);
3477        swap(*__first, *__m);
3478        return __m;
3479    }
3480    if (__len <= __p.second)
3481    {   // The buffer is big enough to use
3482        typedef typename iterator_traits<_BidirectionalIterator>::value_type value_type;
3483        __destruct_n __d(0);
3484        unique_ptr<value_type, __destruct_n&> __h(__p.first, __d);
3485        // Move the falses into the temporary buffer, and the trues to the front of the line
3486        // Update __first to always point to the end of the trues
3487        value_type* __t = __p.first;
3488        ::new(__t) value_type(_VSTD::move(*__first));
3489        __d.__incr((value_type*)0);
3490        ++__t;
3491        _BidirectionalIterator __i = __first;
3492        while (++__i != __last)
3493        {
3494            if (__pred(*__i))
3495            {
3496                *__first = _VSTD::move(*__i);
3497                ++__first;
3498            }
3499            else
3500            {
3501                ::new(__t) value_type(_VSTD::move(*__i));
3502                __d.__incr((value_type*)0);
3503                ++__t;
3504            }
3505        }
3506        // move *__last, known to be true
3507        *__first = _VSTD::move(*__i);
3508        __i = ++__first;
3509        // All trues now at start of range, all falses in buffer
3510        // Move falses back into range, but don't mess up __first which points to first false
3511        for (value_type* __t2 = __p.first; __t2 < __t; ++__t2, ++__i)
3512            *__i = _VSTD::move(*__t2);
3513        // __h destructs moved-from values out of the temp buffer, but doesn't deallocate buffer
3514        return __first;
3515    }
3516    // Else not enough buffer, do in place
3517    // __len >= 4
3518    _BidirectionalIterator __m = __first;
3519    _Distance __len2 = __len / 2;  // __len2 >= 2
3520    _VSTD::advance(__m, __len2);
3521    // recurse on [__first, __m-1], except reduce __m-1 until *(__m-1) is true, *__first know to be false
3522    // F????????????????T
3523    // f       m        l
3524    _BidirectionalIterator __m1 = __m;
3525    _BidirectionalIterator __first_false = __first;
3526    _Distance __len_half = __len2;
3527    while (!__pred(*--__m1))
3528    {
3529        if (__m1 == __first)
3530            goto __first_half_done;
3531        --__len_half;
3532    }
3533    // F???TFFF?????????T
3534    // f   m1  m        l
3535    typedef typename add_lvalue_reference<_Predicate>::type _PredRef;
3536    __first_false = __stable_partition<_PredRef>(__first, __m1, __pred, __len_half, __p, __bit);
3537__first_half_done:
3538    // TTTFFFFF?????????T
3539    // f  ff   m        l
3540    // recurse on [__m, __last], except increase __m until *(__m) is false, *__last know to be true
3541    __m1 = __m;
3542    _BidirectionalIterator __second_false = __last;
3543    ++__second_false;
3544    __len_half = __len - __len2;
3545    while (__pred(*__m1))
3546    {
3547        if (++__m1 == __last)
3548            goto __second_half_done;
3549        --__len_half;
3550    }
3551    // TTTFFFFFTTTF?????T
3552    // f  ff   m  m1    l
3553    __second_false = __stable_partition<_PredRef>(__m1, __last, __pred, __len_half, __p, __bit);
3554__second_half_done:
3555    // TTTFFFFFTTTTTFFFFF
3556    // f  ff   m    sf  l
3557    return _VSTD::rotate(__first_false, __m, __second_false);
3558    // TTTTTTTTFFFFFFFFFF
3559    //         |
3560}
3561
3562template <class _Predicate, class _BidirectionalIterator>
3563_BidirectionalIterator
3564__stable_partition(_BidirectionalIterator __first, _BidirectionalIterator __last, _Predicate __pred,
3565                   bidirectional_iterator_tag)
3566{
3567    typedef typename iterator_traits<_BidirectionalIterator>::difference_type difference_type;
3568    typedef typename iterator_traits<_BidirectionalIterator>::value_type value_type;
3569    const difference_type __alloc_limit = 4;  // might want to make this a function of trivial assignment
3570    // Either prove all true and return __first or point to first false
3571    while (true)
3572    {
3573        if (__first == __last)
3574            return __first;
3575        if (!__pred(*__first))
3576            break;
3577        ++__first;
3578    }
3579    // __first points to first false, everything prior to __first is already set.
3580    // Either prove [__first, __last) is all false and return __first, or point __last to last true
3581    do
3582    {
3583        if (__first == --__last)
3584            return __first;
3585    } while (!__pred(*__last));
3586    // We now have a reduced range [__first, __last]
3587    // *__first is known to be false
3588    // *__last is known to be true
3589    // __len >= 2
3590    difference_type __len = _VSTD::distance(__first, __last) + 1;
3591    pair<value_type*, ptrdiff_t> __p(0, 0);
3592    unique_ptr<value_type, __return_temporary_buffer> __h;
3593    if (__len >= __alloc_limit)
3594    {
3595        __p = _VSTD::get_temporary_buffer<value_type>(__len);
3596        __h.reset(__p.first);
3597    }
3598    return __stable_partition<typename add_lvalue_reference<_Predicate>::type>
3599                             (__first, __last, __pred, __len, __p, bidirectional_iterator_tag());
3600}
3601
3602template <class _ForwardIterator, class _Predicate>
3603inline _LIBCPP_INLINE_VISIBILITY
3604_ForwardIterator
3605stable_partition(_ForwardIterator __first, _ForwardIterator __last, _Predicate __pred)
3606{
3607    return __stable_partition<typename add_lvalue_reference<_Predicate>::type>
3608                             (__first, __last, __pred, typename iterator_traits<_ForwardIterator>::iterator_category());
3609}
3610
3611// is_sorted_until
3612
3613template <class _ForwardIterator, class _Compare>
3614_LIBCPP_NODISCARD_EXT _LIBCPP_CONSTEXPR_AFTER_CXX17 _ForwardIterator
3615is_sorted_until(_ForwardIterator __first, _ForwardIterator __last, _Compare __comp)
3616{
3617    if (__first != __last)
3618    {
3619        _ForwardIterator __i = __first;
3620        while (++__i != __last)
3621        {
3622            if (__comp(*__i, *__first))
3623                return __i;
3624            __first = __i;
3625        }
3626    }
3627    return __last;
3628}
3629
3630template<class _ForwardIterator>
3631_LIBCPP_NODISCARD_EXT inline
3632_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
3633_ForwardIterator
3634is_sorted_until(_ForwardIterator __first, _ForwardIterator __last)
3635{
3636    return _VSTD::is_sorted_until(__first, __last, __less<typename iterator_traits<_ForwardIterator>::value_type>());
3637}
3638
3639// is_sorted
3640
3641template <class _ForwardIterator, class _Compare>
3642_LIBCPP_NODISCARD_EXT inline
3643_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
3644bool
3645is_sorted(_ForwardIterator __first, _ForwardIterator __last, _Compare __comp)
3646{
3647    return _VSTD::is_sorted_until(__first, __last, __comp) == __last;
3648}
3649
3650template<class _ForwardIterator>
3651_LIBCPP_NODISCARD_EXT inline
3652_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
3653bool
3654is_sorted(_ForwardIterator __first, _ForwardIterator __last)
3655{
3656    return _VSTD::is_sorted(__first, __last, __less<typename iterator_traits<_ForwardIterator>::value_type>());
3657}
3658
3659// sort
3660
3661// stable, 2-3 compares, 0-2 swaps
3662
3663template <class _Compare, class _ForwardIterator>
3664unsigned
3665__sort3(_ForwardIterator __x, _ForwardIterator __y, _ForwardIterator __z, _Compare __c)
3666{
3667    unsigned __r = 0;
3668    if (!__c(*__y, *__x))          // if x <= y
3669    {
3670        if (!__c(*__z, *__y))      // if y <= z
3671            return __r;            // x <= y && y <= z
3672                                   // x <= y && y > z
3673        swap(*__y, *__z);          // x <= z && y < z
3674        __r = 1;
3675        if (__c(*__y, *__x))       // if x > y
3676        {
3677            swap(*__x, *__y);      // x < y && y <= z
3678            __r = 2;
3679        }
3680        return __r;                // x <= y && y < z
3681    }
3682    if (__c(*__z, *__y))           // x > y, if y > z
3683    {
3684        swap(*__x, *__z);          // x < y && y < z
3685        __r = 1;
3686        return __r;
3687    }
3688    swap(*__x, *__y);              // x > y && y <= z
3689    __r = 1;                       // x < y && x <= z
3690    if (__c(*__z, *__y))           // if y > z
3691    {
3692        swap(*__y, *__z);          // x <= y && y < z
3693        __r = 2;
3694    }
3695    return __r;
3696}                                  // x <= y && y <= z
3697
3698// stable, 3-6 compares, 0-5 swaps
3699
3700template <class _Compare, class _ForwardIterator>
3701unsigned
3702__sort4(_ForwardIterator __x1, _ForwardIterator __x2, _ForwardIterator __x3,
3703            _ForwardIterator __x4, _Compare __c)
3704{
3705    unsigned __r = __sort3<_Compare>(__x1, __x2, __x3, __c);
3706    if (__c(*__x4, *__x3))
3707    {
3708        swap(*__x3, *__x4);
3709        ++__r;
3710        if (__c(*__x3, *__x2))
3711        {
3712            swap(*__x2, *__x3);
3713            ++__r;
3714            if (__c(*__x2, *__x1))
3715            {
3716                swap(*__x1, *__x2);
3717                ++__r;
3718            }
3719        }
3720    }
3721    return __r;
3722}
3723
3724// stable, 4-10 compares, 0-9 swaps
3725
3726template <class _Compare, class _ForwardIterator>
3727_LIBCPP_HIDDEN
3728unsigned
3729__sort5(_ForwardIterator __x1, _ForwardIterator __x2, _ForwardIterator __x3,
3730            _ForwardIterator __x4, _ForwardIterator __x5, _Compare __c)
3731{
3732    unsigned __r = __sort4<_Compare>(__x1, __x2, __x3, __x4, __c);
3733    if (__c(*__x5, *__x4))
3734    {
3735        swap(*__x4, *__x5);
3736        ++__r;
3737        if (__c(*__x4, *__x3))
3738        {
3739            swap(*__x3, *__x4);
3740            ++__r;
3741            if (__c(*__x3, *__x2))
3742            {
3743                swap(*__x2, *__x3);
3744                ++__r;
3745                if (__c(*__x2, *__x1))
3746                {
3747                    swap(*__x1, *__x2);
3748                    ++__r;
3749                }
3750            }
3751        }
3752    }
3753    return __r;
3754}
3755
3756// Assumes size > 0
3757template <class _Compare, class _BirdirectionalIterator>
3758void
3759__selection_sort(_BirdirectionalIterator __first, _BirdirectionalIterator __last, _Compare __comp)
3760{
3761    _BirdirectionalIterator __lm1 = __last;
3762    for (--__lm1; __first != __lm1; ++__first)
3763    {
3764        _BirdirectionalIterator __i = _VSTD::min_element<_BirdirectionalIterator,
3765                                                        typename add_lvalue_reference<_Compare>::type>
3766                                                       (__first, __last, __comp);
3767        if (__i != __first)
3768            swap(*__first, *__i);
3769    }
3770}
3771
3772template <class _Compare, class _BirdirectionalIterator>
3773void
3774__insertion_sort(_BirdirectionalIterator __first, _BirdirectionalIterator __last, _Compare __comp)
3775{
3776    typedef typename iterator_traits<_BirdirectionalIterator>::value_type value_type;
3777    if (__first != __last)
3778    {
3779        _BirdirectionalIterator __i = __first;
3780        for (++__i; __i != __last; ++__i)
3781        {
3782            _BirdirectionalIterator __j = __i;
3783            value_type __t(_VSTD::move(*__j));
3784            for (_BirdirectionalIterator __k = __i; __k != __first && __comp(__t,  *--__k); --__j)
3785                *__j = _VSTD::move(*__k);
3786            *__j = _VSTD::move(__t);
3787        }
3788    }
3789}
3790
3791template <class _Compare, class _RandomAccessIterator>
3792void
3793__insertion_sort_3(_RandomAccessIterator __first, _RandomAccessIterator __last, _Compare __comp)
3794{
3795    typedef typename iterator_traits<_RandomAccessIterator>::value_type value_type;
3796    _RandomAccessIterator __j = __first+2;
3797    __sort3<_Compare>(__first, __first+1, __j, __comp);
3798    for (_RandomAccessIterator __i = __j+1; __i != __last; ++__i)
3799    {
3800        if (__comp(*__i, *__j))
3801        {
3802            value_type __t(_VSTD::move(*__i));
3803            _RandomAccessIterator __k = __j;
3804            __j = __i;
3805            do
3806            {
3807                *__j = _VSTD::move(*__k);
3808                __j = __k;
3809            } while (__j != __first && __comp(__t, *--__k));
3810            *__j = _VSTD::move(__t);
3811        }
3812        __j = __i;
3813    }
3814}
3815
3816template <class _Compare, class _RandomAccessIterator>
3817bool
3818__insertion_sort_incomplete(_RandomAccessIterator __first, _RandomAccessIterator __last, _Compare __comp)
3819{
3820    switch (__last - __first)
3821    {
3822    case 0:
3823    case 1:
3824        return true;
3825    case 2:
3826        if (__comp(*--__last, *__first))
3827            swap(*__first, *__last);
3828        return true;
3829    case 3:
3830        _VSTD::__sort3<_Compare>(__first, __first+1, --__last, __comp);
3831        return true;
3832    case 4:
3833        _VSTD::__sort4<_Compare>(__first, __first+1, __first+2, --__last, __comp);
3834        return true;
3835    case 5:
3836        _VSTD::__sort5<_Compare>(__first, __first+1, __first+2, __first+3, --__last, __comp);
3837        return true;
3838    }
3839    typedef typename iterator_traits<_RandomAccessIterator>::value_type value_type;
3840    _RandomAccessIterator __j = __first+2;
3841    __sort3<_Compare>(__first, __first+1, __j, __comp);
3842    const unsigned __limit = 8;
3843    unsigned __count = 0;
3844    for (_RandomAccessIterator __i = __j+1; __i != __last; ++__i)
3845    {
3846        if (__comp(*__i, *__j))
3847        {
3848            value_type __t(_VSTD::move(*__i));
3849            _RandomAccessIterator __k = __j;
3850            __j = __i;
3851            do
3852            {
3853                *__j = _VSTD::move(*__k);
3854                __j = __k;
3855            } while (__j != __first && __comp(__t, *--__k));
3856            *__j = _VSTD::move(__t);
3857            if (++__count == __limit)
3858                return ++__i == __last;
3859        }
3860        __j = __i;
3861    }
3862    return true;
3863}
3864
3865template <class _Compare, class _BirdirectionalIterator>
3866void
3867__insertion_sort_move(_BirdirectionalIterator __first1, _BirdirectionalIterator __last1,
3868                      typename iterator_traits<_BirdirectionalIterator>::value_type* __first2, _Compare __comp)
3869{
3870    typedef typename iterator_traits<_BirdirectionalIterator>::value_type value_type;
3871    if (__first1 != __last1)
3872    {
3873        __destruct_n __d(0);
3874        unique_ptr<value_type, __destruct_n&> __h(__first2, __d);
3875        value_type* __last2 = __first2;
3876        ::new(__last2) value_type(_VSTD::move(*__first1));
3877        __d.__incr((value_type*)0);
3878        for (++__last2; ++__first1 != __last1; ++__last2)
3879        {
3880            value_type* __j2 = __last2;
3881            value_type* __i2 = __j2;
3882            if (__comp(*__first1, *--__i2))
3883            {
3884                ::new(__j2) value_type(_VSTD::move(*__i2));
3885                __d.__incr((value_type*)0);
3886                for (--__j2; __i2 != __first2 && __comp(*__first1,  *--__i2); --__j2)
3887                    *__j2 = _VSTD::move(*__i2);
3888                *__j2 = _VSTD::move(*__first1);
3889            }
3890            else
3891            {
3892                ::new(__j2) value_type(_VSTD::move(*__first1));
3893                __d.__incr((value_type*)0);
3894            }
3895        }
3896        __h.release();
3897    }
3898}
3899
3900template <class _Compare, class _RandomAccessIterator>
3901void
3902__sort(_RandomAccessIterator __first, _RandomAccessIterator __last, _Compare __comp)
3903{
3904    // _Compare is known to be a reference type
3905    typedef typename iterator_traits<_RandomAccessIterator>::difference_type difference_type;
3906    typedef typename iterator_traits<_RandomAccessIterator>::value_type value_type;
3907    const difference_type __limit = is_trivially_copy_constructible<value_type>::value &&
3908                                    is_trivially_copy_assignable<value_type>::value ? 30 : 6;
3909    while (true)
3910    {
3911    __restart:
3912        difference_type __len = __last - __first;
3913        switch (__len)
3914        {
3915        case 0:
3916        case 1:
3917            return;
3918        case 2:
3919            if (__comp(*--__last, *__first))
3920                swap(*__first, *__last);
3921            return;
3922        case 3:
3923            _VSTD::__sort3<_Compare>(__first, __first+1, --__last, __comp);
3924            return;
3925        case 4:
3926            _VSTD::__sort4<_Compare>(__first, __first+1, __first+2, --__last, __comp);
3927            return;
3928        case 5:
3929            _VSTD::__sort5<_Compare>(__first, __first+1, __first+2, __first+3, --__last, __comp);
3930            return;
3931        }
3932        if (__len <= __limit)
3933        {
3934            _VSTD::__insertion_sort_3<_Compare>(__first, __last, __comp);
3935            return;
3936        }
3937        // __len > 5
3938        _RandomAccessIterator __m = __first;
3939        _RandomAccessIterator __lm1 = __last;
3940        --__lm1;
3941        unsigned __n_swaps;
3942        {
3943        difference_type __delta;
3944        if (__len >= 1000)
3945        {
3946            __delta = __len/2;
3947            __m += __delta;
3948            __delta /= 2;
3949            __n_swaps = _VSTD::__sort5<_Compare>(__first, __first + __delta, __m, __m+__delta, __lm1, __comp);
3950        }
3951        else
3952        {
3953            __delta = __len/2;
3954            __m += __delta;
3955            __n_swaps = _VSTD::__sort3<_Compare>(__first, __m, __lm1, __comp);
3956        }
3957        }
3958        // *__m is median
3959        // partition [__first, __m) < *__m and *__m <= [__m, __last)
3960        // (this inhibits tossing elements equivalent to __m around unnecessarily)
3961        _RandomAccessIterator __i = __first;
3962        _RandomAccessIterator __j = __lm1;
3963        // j points beyond range to be tested, *__m is known to be <= *__lm1
3964        // The search going up is known to be guarded but the search coming down isn't.
3965        // Prime the downward search with a guard.
3966        if (!__comp(*__i, *__m))  // if *__first == *__m
3967        {
3968            // *__first == *__m, *__first doesn't go in first part
3969            // manually guard downward moving __j against __i
3970            while (true)
3971            {
3972                if (__i == --__j)
3973                {
3974                    // *__first == *__m, *__m <= all other elements
3975                    // Parition instead into [__first, __i) == *__first and *__first < [__i, __last)
3976                    ++__i;  // __first + 1
3977                    __j = __last;
3978                    if (!__comp(*__first, *--__j))  // we need a guard if *__first == *(__last-1)
3979                    {
3980                        while (true)
3981                        {
3982                            if (__i == __j)
3983                                return;  // [__first, __last) all equivalent elements
3984                            if (__comp(*__first, *__i))
3985                            {
3986                                swap(*__i, *__j);
3987                                ++__n_swaps;
3988                                ++__i;
3989                                break;
3990                            }
3991                            ++__i;
3992                        }
3993                    }
3994                    // [__first, __i) == *__first and *__first < [__j, __last) and __j == __last - 1
3995                    if (__i == __j)
3996                        return;
3997                    while (true)
3998                    {
3999                        while (!__comp(*__first, *__i))
4000                            ++__i;
4001                        while (__comp(*__first, *--__j))
4002                            ;
4003                        if (__i >= __j)
4004                            break;
4005                        swap(*__i, *__j);
4006                        ++__n_swaps;
4007                        ++__i;
4008                    }
4009                    // [__first, __i) == *__first and *__first < [__i, __last)
4010                    // The first part is sorted, sort the secod part
4011                    // _VSTD::__sort<_Compare>(__i, __last, __comp);
4012                    __first = __i;
4013                    goto __restart;
4014                }
4015                if (__comp(*__j, *__m))
4016                {
4017                    swap(*__i, *__j);
4018                    ++__n_swaps;
4019                    break;  // found guard for downward moving __j, now use unguarded partition
4020                }
4021            }
4022        }
4023        // It is known that *__i < *__m
4024        ++__i;
4025        // j points beyond range to be tested, *__m is known to be <= *__lm1
4026        // if not yet partitioned...
4027        if (__i < __j)
4028        {
4029            // known that *(__i - 1) < *__m
4030            // known that __i <= __m
4031            while (true)
4032            {
4033                // __m still guards upward moving __i
4034                while (__comp(*__i, *__m))
4035                    ++__i;
4036                // It is now known that a guard exists for downward moving __j
4037                while (!__comp(*--__j, *__m))
4038                    ;
4039                if (__i > __j)
4040                    break;
4041                swap(*__i, *__j);
4042                ++__n_swaps;
4043                // It is known that __m != __j
4044                // If __m just moved, follow it
4045                if (__m == __i)
4046                    __m = __j;
4047                ++__i;
4048            }
4049        }
4050        // [__first, __i) < *__m and *__m <= [__i, __last)
4051        if (__i != __m && __comp(*__m, *__i))
4052        {
4053            swap(*__i, *__m);
4054            ++__n_swaps;
4055        }
4056        // [__first, __i) < *__i and *__i <= [__i+1, __last)
4057        // If we were given a perfect partition, see if insertion sort is quick...
4058        if (__n_swaps == 0)
4059        {
4060            bool __fs = _VSTD::__insertion_sort_incomplete<_Compare>(__first, __i, __comp);
4061            if (_VSTD::__insertion_sort_incomplete<_Compare>(__i+1, __last, __comp))
4062            {
4063                if (__fs)
4064                    return;
4065                __last = __i;
4066                continue;
4067            }
4068            else
4069            {
4070                if (__fs)
4071                {
4072                    __first = ++__i;
4073                    continue;
4074                }
4075            }
4076        }
4077        // sort smaller range with recursive call and larger with tail recursion elimination
4078        if (__i - __first < __last - __i)
4079        {
4080            _VSTD::__sort<_Compare>(__first, __i, __comp);
4081            // _VSTD::__sort<_Compare>(__i+1, __last, __comp);
4082            __first = ++__i;
4083        }
4084        else
4085        {
4086            _VSTD::__sort<_Compare>(__i+1, __last, __comp);
4087            // _VSTD::__sort<_Compare>(__first, __i, __comp);
4088            __last = __i;
4089        }
4090    }
4091}
4092
4093// This forwarder keeps the top call and the recursive calls using the same instantiation, forcing a reference _Compare
4094template <class _RandomAccessIterator, class _Compare>
4095inline _LIBCPP_INLINE_VISIBILITY
4096void
4097sort(_RandomAccessIterator __first, _RandomAccessIterator __last, _Compare __comp)
4098{
4099    typedef typename __comp_ref_type<_Compare>::type _Comp_ref;
4100    _VSTD::__sort<_Comp_ref>(__first, __last, _Comp_ref(__comp));
4101}
4102
4103template <class _RandomAccessIterator>
4104inline _LIBCPP_INLINE_VISIBILITY
4105void
4106sort(_RandomAccessIterator __first, _RandomAccessIterator __last)
4107{
4108    _VSTD::sort(__first, __last, __less<typename iterator_traits<_RandomAccessIterator>::value_type>());
4109}
4110
4111template <class _Tp>
4112inline _LIBCPP_INLINE_VISIBILITY
4113void
4114sort(_Tp** __first, _Tp** __last)
4115{
4116    _VSTD::sort((size_t*)__first, (size_t*)__last, __less<size_t>());
4117}
4118
4119template <class _Tp>
4120inline _LIBCPP_INLINE_VISIBILITY
4121void
4122sort(__wrap_iter<_Tp*> __first, __wrap_iter<_Tp*> __last)
4123{
4124    _VSTD::sort(__first.base(), __last.base());
4125}
4126
4127template <class _Tp, class _Compare>
4128inline _LIBCPP_INLINE_VISIBILITY
4129void
4130sort(__wrap_iter<_Tp*> __first, __wrap_iter<_Tp*> __last, _Compare __comp)
4131{
4132    typedef typename add_lvalue_reference<_Compare>::type _Comp_ref;
4133    _VSTD::sort<_Tp*, _Comp_ref>(__first.base(), __last.base(), __comp);
4134}
4135
4136_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS void __sort<__less<char>&, char*>(char*, char*, __less<char>&))
4137_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS void __sort<__less<wchar_t>&, wchar_t*>(wchar_t*, wchar_t*, __less<wchar_t>&))
4138_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS void __sort<__less<signed char>&, signed char*>(signed char*, signed char*, __less<signed char>&))
4139_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS void __sort<__less<unsigned char>&, unsigned char*>(unsigned char*, unsigned char*, __less<unsigned char>&))
4140_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS void __sort<__less<short>&, short*>(short*, short*, __less<short>&))
4141_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS void __sort<__less<unsigned short>&, unsigned short*>(unsigned short*, unsigned short*, __less<unsigned short>&))
4142_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS void __sort<__less<int>&, int*>(int*, int*, __less<int>&))
4143_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS void __sort<__less<unsigned>&, unsigned*>(unsigned*, unsigned*, __less<unsigned>&))
4144_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS void __sort<__less<long>&, long*>(long*, long*, __less<long>&))
4145_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS void __sort<__less<unsigned long>&, unsigned long*>(unsigned long*, unsigned long*, __less<unsigned long>&))
4146_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS void __sort<__less<long long>&, long long*>(long long*, long long*, __less<long long>&))
4147_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS void __sort<__less<unsigned long long>&, unsigned long long*>(unsigned long long*, unsigned long long*, __less<unsigned long long>&))
4148_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS void __sort<__less<float>&, float*>(float*, float*, __less<float>&))
4149_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS void __sort<__less<double>&, double*>(double*, double*, __less<double>&))
4150_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS void __sort<__less<long double>&, long double*>(long double*, long double*, __less<long double>&))
4151
4152_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS bool __insertion_sort_incomplete<__less<char>&, char*>(char*, char*, __less<char>&))
4153_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS bool __insertion_sort_incomplete<__less<wchar_t>&, wchar_t*>(wchar_t*, wchar_t*, __less<wchar_t>&))
4154_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS bool __insertion_sort_incomplete<__less<signed char>&, signed char*>(signed char*, signed char*, __less<signed char>&))
4155_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS bool __insertion_sort_incomplete<__less<unsigned char>&, unsigned char*>(unsigned char*, unsigned char*, __less<unsigned char>&))
4156_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS bool __insertion_sort_incomplete<__less<short>&, short*>(short*, short*, __less<short>&))
4157_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS bool __insertion_sort_incomplete<__less<unsigned short>&, unsigned short*>(unsigned short*, unsigned short*, __less<unsigned short>&))
4158_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS bool __insertion_sort_incomplete<__less<int>&, int*>(int*, int*, __less<int>&))
4159_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS bool __insertion_sort_incomplete<__less<unsigned>&, unsigned*>(unsigned*, unsigned*, __less<unsigned>&))
4160_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS bool __insertion_sort_incomplete<__less<long>&, long*>(long*, long*, __less<long>&))
4161_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS bool __insertion_sort_incomplete<__less<unsigned long>&, unsigned long*>(unsigned long*, unsigned long*, __less<unsigned long>&))
4162_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS bool __insertion_sort_incomplete<__less<long long>&, long long*>(long long*, long long*, __less<long long>&))
4163_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS bool __insertion_sort_incomplete<__less<unsigned long long>&, unsigned long long*>(unsigned long long*, unsigned long long*, __less<unsigned long long>&))
4164_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS bool __insertion_sort_incomplete<__less<float>&, float*>(float*, float*, __less<float>&))
4165_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS bool __insertion_sort_incomplete<__less<double>&, double*>(double*, double*, __less<double>&))
4166_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS bool __insertion_sort_incomplete<__less<long double>&, long double*>(long double*, long double*, __less<long double>&))
4167
4168_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS unsigned __sort5<__less<long double>&, long double*>(long double*, long double*, long double*, long double*, long double*, __less<long double>&))
4169
4170// lower_bound
4171
4172template <class _Compare, class _ForwardIterator, class _Tp>
4173_LIBCPP_CONSTEXPR_AFTER_CXX17 _ForwardIterator
4174__lower_bound(_ForwardIterator __first, _ForwardIterator __last, const _Tp& __value_, _Compare __comp)
4175{
4176    typedef typename iterator_traits<_ForwardIterator>::difference_type difference_type;
4177    difference_type __len = _VSTD::distance(__first, __last);
4178    while (__len != 0)
4179    {
4180        difference_type __l2 = _VSTD::__half_positive(__len);
4181        _ForwardIterator __m = __first;
4182        _VSTD::advance(__m, __l2);
4183        if (__comp(*__m, __value_))
4184        {
4185            __first = ++__m;
4186            __len -= __l2 + 1;
4187        }
4188        else
4189            __len = __l2;
4190    }
4191    return __first;
4192}
4193
4194template <class _ForwardIterator, class _Tp, class _Compare>
4195_LIBCPP_NODISCARD_EXT inline
4196_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
4197_ForwardIterator
4198lower_bound(_ForwardIterator __first, _ForwardIterator __last, const _Tp& __value_, _Compare __comp)
4199{
4200    typedef typename add_lvalue_reference<_Compare>::type _Comp_ref;
4201    return __lower_bound<_Comp_ref>(__first, __last, __value_, __comp);
4202}
4203
4204template <class _ForwardIterator, class _Tp>
4205_LIBCPP_NODISCARD_EXT inline
4206_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
4207_ForwardIterator
4208lower_bound(_ForwardIterator __first, _ForwardIterator __last, const _Tp& __value_)
4209{
4210    return _VSTD::lower_bound(__first, __last, __value_,
4211                             __less<typename iterator_traits<_ForwardIterator>::value_type, _Tp>());
4212}
4213
4214// upper_bound
4215
4216template <class _Compare, class _ForwardIterator, class _Tp>
4217_LIBCPP_CONSTEXPR_AFTER_CXX17 _ForwardIterator
4218__upper_bound(_ForwardIterator __first, _ForwardIterator __last, const _Tp& __value_, _Compare __comp)
4219{
4220    typedef typename iterator_traits<_ForwardIterator>::difference_type difference_type;
4221    difference_type __len = _VSTD::distance(__first, __last);
4222    while (__len != 0)
4223    {
4224        difference_type __l2 = _VSTD::__half_positive(__len);
4225        _ForwardIterator __m = __first;
4226        _VSTD::advance(__m, __l2);
4227        if (__comp(__value_, *__m))
4228            __len = __l2;
4229        else
4230        {
4231            __first = ++__m;
4232            __len -= __l2 + 1;
4233        }
4234    }
4235    return __first;
4236}
4237
4238template <class _ForwardIterator, class _Tp, class _Compare>
4239_LIBCPP_NODISCARD_EXT inline
4240_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
4241_ForwardIterator
4242upper_bound(_ForwardIterator __first, _ForwardIterator __last, const _Tp& __value_, _Compare __comp)
4243{
4244    typedef typename add_lvalue_reference<_Compare>::type _Comp_ref;
4245    return __upper_bound<_Comp_ref>(__first, __last, __value_, __comp);
4246}
4247
4248template <class _ForwardIterator, class _Tp>
4249_LIBCPP_NODISCARD_EXT inline
4250_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
4251_ForwardIterator
4252upper_bound(_ForwardIterator __first, _ForwardIterator __last, const _Tp& __value_)
4253{
4254    return _VSTD::upper_bound(__first, __last, __value_,
4255                             __less<_Tp, typename iterator_traits<_ForwardIterator>::value_type>());
4256}
4257
4258// equal_range
4259
4260template <class _Compare, class _ForwardIterator, class _Tp>
4261_LIBCPP_CONSTEXPR_AFTER_CXX17 pair<_ForwardIterator, _ForwardIterator>
4262__equal_range(_ForwardIterator __first, _ForwardIterator __last, const _Tp& __value_, _Compare __comp)
4263{
4264    typedef typename iterator_traits<_ForwardIterator>::difference_type difference_type;
4265    difference_type __len = _VSTD::distance(__first, __last);
4266    while (__len != 0)
4267    {
4268        difference_type __l2 = _VSTD::__half_positive(__len);
4269        _ForwardIterator __m = __first;
4270        _VSTD::advance(__m, __l2);
4271        if (__comp(*__m, __value_))
4272        {
4273            __first = ++__m;
4274            __len -= __l2 + 1;
4275        }
4276        else if (__comp(__value_, *__m))
4277        {
4278            __last = __m;
4279            __len = __l2;
4280        }
4281        else
4282        {
4283            _ForwardIterator __mp1 = __m;
4284            return pair<_ForwardIterator, _ForwardIterator>
4285                   (
4286                      __lower_bound<_Compare>(__first, __m, __value_, __comp),
4287                      __upper_bound<_Compare>(++__mp1, __last, __value_, __comp)
4288                   );
4289        }
4290    }
4291    return pair<_ForwardIterator, _ForwardIterator>(__first, __first);
4292}
4293
4294template <class _ForwardIterator, class _Tp, class _Compare>
4295_LIBCPP_NODISCARD_EXT inline
4296_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
4297pair<_ForwardIterator, _ForwardIterator>
4298equal_range(_ForwardIterator __first, _ForwardIterator __last, const _Tp& __value_, _Compare __comp)
4299{
4300    typedef typename __comp_ref_type<_Compare>::type _Comp_ref;
4301    return __equal_range<_Comp_ref>(__first, __last, __value_, __comp);
4302}
4303
4304template <class _ForwardIterator, class _Tp>
4305_LIBCPP_NODISCARD_EXT inline
4306_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
4307pair<_ForwardIterator, _ForwardIterator>
4308equal_range(_ForwardIterator __first, _ForwardIterator __last, const _Tp& __value_)
4309{
4310    return _VSTD::equal_range(__first, __last, __value_,
4311                             __less<typename iterator_traits<_ForwardIterator>::value_type, _Tp>());
4312}
4313
4314// binary_search
4315
4316template <class _Compare, class _ForwardIterator, class _Tp>
4317inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
4318bool
4319__binary_search(_ForwardIterator __first, _ForwardIterator __last, const _Tp& __value_, _Compare __comp)
4320{
4321    __first = __lower_bound<_Compare>(__first, __last, __value_, __comp);
4322    return __first != __last && !__comp(__value_, *__first);
4323}
4324
4325template <class _ForwardIterator, class _Tp, class _Compare>
4326_LIBCPP_NODISCARD_EXT inline
4327_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
4328bool
4329binary_search(_ForwardIterator __first, _ForwardIterator __last, const _Tp& __value_, _Compare __comp)
4330{
4331    typedef typename __comp_ref_type<_Compare>::type _Comp_ref;
4332    return __binary_search<_Comp_ref>(__first, __last, __value_, __comp);
4333}
4334
4335template <class _ForwardIterator, class _Tp>
4336_LIBCPP_NODISCARD_EXT inline
4337_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
4338bool
4339binary_search(_ForwardIterator __first, _ForwardIterator __last, const _Tp& __value_)
4340{
4341    return _VSTD::binary_search(__first, __last, __value_,
4342                             __less<typename iterator_traits<_ForwardIterator>::value_type, _Tp>());
4343}
4344
4345// merge
4346
4347template <class _Compare, class _InputIterator1, class _InputIterator2, class _OutputIterator>
4348_OutputIterator
4349__merge(_InputIterator1 __first1, _InputIterator1 __last1,
4350        _InputIterator2 __first2, _InputIterator2 __last2, _OutputIterator __result, _Compare __comp)
4351{
4352    for (; __first1 != __last1; ++__result)
4353    {
4354        if (__first2 == __last2)
4355            return _VSTD::copy(__first1, __last1, __result);
4356        if (__comp(*__first2, *__first1))
4357        {
4358            *__result = *__first2;
4359            ++__first2;
4360        }
4361        else
4362        {
4363            *__result = *__first1;
4364            ++__first1;
4365        }
4366    }
4367    return _VSTD::copy(__first2, __last2, __result);
4368}
4369
4370template <class _InputIterator1, class _InputIterator2, class _OutputIterator, class _Compare>
4371inline _LIBCPP_INLINE_VISIBILITY
4372_OutputIterator
4373merge(_InputIterator1 __first1, _InputIterator1 __last1,
4374      _InputIterator2 __first2, _InputIterator2 __last2, _OutputIterator __result, _Compare __comp)
4375{
4376    typedef typename __comp_ref_type<_Compare>::type _Comp_ref;
4377    return _VSTD::__merge<_Comp_ref>(__first1, __last1, __first2, __last2, __result, __comp);
4378}
4379
4380template <class _InputIterator1, class _InputIterator2, class _OutputIterator>
4381inline _LIBCPP_INLINE_VISIBILITY
4382_OutputIterator
4383merge(_InputIterator1 __first1, _InputIterator1 __last1,
4384      _InputIterator2 __first2, _InputIterator2 __last2, _OutputIterator __result)
4385{
4386    typedef typename iterator_traits<_InputIterator1>::value_type __v1;
4387    typedef typename iterator_traits<_InputIterator2>::value_type __v2;
4388    return merge(__first1, __last1, __first2, __last2, __result, __less<__v1, __v2>());
4389}
4390
4391// inplace_merge
4392
4393template <class _Compare, class _InputIterator1, class _InputIterator2,
4394          class _OutputIterator>
4395void __half_inplace_merge(_InputIterator1 __first1, _InputIterator1 __last1,
4396                          _InputIterator2 __first2, _InputIterator2 __last2,
4397                          _OutputIterator __result, _Compare __comp)
4398{
4399    for (; __first1 != __last1; ++__result)
4400    {
4401        if (__first2 == __last2)
4402        {
4403            _VSTD::move(__first1, __last1, __result);
4404            return;
4405        }
4406
4407        if (__comp(*__first2, *__first1))
4408        {
4409            *__result = _VSTD::move(*__first2);
4410            ++__first2;
4411        }
4412        else
4413        {
4414            *__result = _VSTD::move(*__first1);
4415            ++__first1;
4416        }
4417    }
4418    // __first2 through __last2 are already in the right spot.
4419}
4420
4421template <class _Compare, class _BidirectionalIterator>
4422void
4423__buffered_inplace_merge(_BidirectionalIterator __first, _BidirectionalIterator __middle, _BidirectionalIterator __last,
4424                _Compare __comp, typename iterator_traits<_BidirectionalIterator>::difference_type __len1,
4425                                 typename iterator_traits<_BidirectionalIterator>::difference_type __len2,
4426                typename iterator_traits<_BidirectionalIterator>::value_type* __buff)
4427{
4428    typedef typename iterator_traits<_BidirectionalIterator>::value_type value_type;
4429    __destruct_n __d(0);
4430    unique_ptr<value_type, __destruct_n&> __h2(__buff, __d);
4431    if (__len1 <= __len2)
4432    {
4433        value_type* __p = __buff;
4434        for (_BidirectionalIterator __i = __first; __i != __middle; __d.__incr((value_type*)0), (void) ++__i, ++__p)
4435            ::new(__p) value_type(_VSTD::move(*__i));
4436        __half_inplace_merge(__buff, __p, __middle, __last, __first, __comp);
4437    }
4438    else
4439    {
4440        value_type* __p = __buff;
4441        for (_BidirectionalIterator __i = __middle; __i != __last; __d.__incr((value_type*)0), (void) ++__i, ++__p)
4442            ::new(__p) value_type(_VSTD::move(*__i));
4443        typedef reverse_iterator<_BidirectionalIterator> _RBi;
4444        typedef reverse_iterator<value_type*> _Rv;
4445        __half_inplace_merge(_Rv(__p), _Rv(__buff),
4446                             _RBi(__middle), _RBi(__first),
4447                             _RBi(__last), __invert<_Compare>(__comp));
4448    }
4449}
4450
4451template <class _Compare, class _BidirectionalIterator>
4452void
4453__inplace_merge(_BidirectionalIterator __first, _BidirectionalIterator __middle, _BidirectionalIterator __last,
4454                _Compare __comp, typename iterator_traits<_BidirectionalIterator>::difference_type __len1,
4455                                 typename iterator_traits<_BidirectionalIterator>::difference_type __len2,
4456                typename iterator_traits<_BidirectionalIterator>::value_type* __buff, ptrdiff_t __buff_size)
4457{
4458    typedef typename iterator_traits<_BidirectionalIterator>::difference_type difference_type;
4459    while (true)
4460    {
4461        // if __middle == __last, we're done
4462        if (__len2 == 0)
4463            return;
4464        if (__len1 <= __buff_size || __len2 <= __buff_size)
4465            return __buffered_inplace_merge<_Compare>
4466                   (__first, __middle, __last, __comp, __len1, __len2, __buff);
4467        // shrink [__first, __middle) as much as possible (with no moves), returning if it shrinks to 0
4468        for (; true; ++__first, (void) --__len1)
4469        {
4470            if (__len1 == 0)
4471                return;
4472            if (__comp(*__middle, *__first))
4473                break;
4474        }
4475        // __first < __middle < __last
4476        // *__first > *__middle
4477        // partition [__first, __m1) [__m1, __middle) [__middle, __m2) [__m2, __last) such that
4478        //     all elements in:
4479        //         [__first, __m1)  <= [__middle, __m2)
4480        //         [__middle, __m2) <  [__m1, __middle)
4481        //         [__m1, __middle) <= [__m2, __last)
4482        //     and __m1 or __m2 is in the middle of its range
4483        _BidirectionalIterator __m1;  // "median" of [__first, __middle)
4484        _BidirectionalIterator __m2;  // "median" of [__middle, __last)
4485        difference_type __len11;      // distance(__first, __m1)
4486        difference_type __len21;      // distance(__middle, __m2)
4487        // binary search smaller range
4488        if (__len1 < __len2)
4489        {   // __len >= 1, __len2 >= 2
4490            __len21 = __len2 / 2;
4491            __m2 = __middle;
4492            _VSTD::advance(__m2, __len21);
4493            __m1 = __upper_bound<_Compare>(__first, __middle, *__m2, __comp);
4494            __len11 = _VSTD::distance(__first, __m1);
4495        }
4496        else
4497        {
4498            if (__len1 == 1)
4499            {   // __len1 >= __len2 && __len2 > 0, therefore __len2 == 1
4500                // It is known *__first > *__middle
4501                swap(*__first, *__middle);
4502                return;
4503            }
4504            // __len1 >= 2, __len2 >= 1
4505            __len11 = __len1 / 2;
4506            __m1 = __first;
4507            _VSTD::advance(__m1, __len11);
4508            __m2 = __lower_bound<_Compare>(__middle, __last, *__m1, __comp);
4509            __len21 = _VSTD::distance(__middle, __m2);
4510        }
4511        difference_type __len12 = __len1 - __len11;  // distance(__m1, __middle)
4512        difference_type __len22 = __len2 - __len21;  // distance(__m2, __last)
4513        // [__first, __m1) [__m1, __middle) [__middle, __m2) [__m2, __last)
4514        // swap middle two partitions
4515        __middle = _VSTD::rotate(__m1, __middle, __m2);
4516        // __len12 and __len21 now have swapped meanings
4517        // merge smaller range with recurisve call and larger with tail recursion elimination
4518        if (__len11 + __len21 < __len12 + __len22)
4519        {
4520            __inplace_merge<_Compare>(__first, __m1, __middle, __comp, __len11, __len21, __buff, __buff_size);
4521//          __inplace_merge<_Compare>(__middle, __m2, __last, __comp, __len12, __len22, __buff, __buff_size);
4522            __first = __middle;
4523            __middle = __m2;
4524            __len1 = __len12;
4525            __len2 = __len22;
4526        }
4527        else
4528        {
4529            __inplace_merge<_Compare>(__middle, __m2, __last, __comp, __len12, __len22, __buff, __buff_size);
4530//          __inplace_merge<_Compare>(__first, __m1, __middle, __comp, __len11, __len21, __buff, __buff_size);
4531            __last = __middle;
4532            __middle = __m1;
4533            __len1 = __len11;
4534            __len2 = __len21;
4535        }
4536    }
4537}
4538
4539template <class _BidirectionalIterator, class _Compare>
4540inline _LIBCPP_INLINE_VISIBILITY
4541void
4542inplace_merge(_BidirectionalIterator __first, _BidirectionalIterator __middle, _BidirectionalIterator __last,
4543              _Compare __comp)
4544{
4545    typedef typename iterator_traits<_BidirectionalIterator>::value_type value_type;
4546    typedef typename iterator_traits<_BidirectionalIterator>::difference_type difference_type;
4547    difference_type __len1 = _VSTD::distance(__first, __middle);
4548    difference_type __len2 = _VSTD::distance(__middle, __last);
4549    difference_type __buf_size = _VSTD::min(__len1, __len2);
4550    pair<value_type*, ptrdiff_t> __buf = _VSTD::get_temporary_buffer<value_type>(__buf_size);
4551    unique_ptr<value_type, __return_temporary_buffer> __h(__buf.first);
4552    typedef typename __comp_ref_type<_Compare>::type _Comp_ref;
4553    return _VSTD::__inplace_merge<_Comp_ref>(__first, __middle, __last, __comp, __len1, __len2,
4554                                            __buf.first, __buf.second);
4555}
4556
4557template <class _BidirectionalIterator>
4558inline _LIBCPP_INLINE_VISIBILITY
4559void
4560inplace_merge(_BidirectionalIterator __first, _BidirectionalIterator __middle, _BidirectionalIterator __last)
4561{
4562    _VSTD::inplace_merge(__first, __middle, __last,
4563                        __less<typename iterator_traits<_BidirectionalIterator>::value_type>());
4564}
4565
4566// stable_sort
4567
4568template <class _Compare, class _InputIterator1, class _InputIterator2>
4569void
4570__merge_move_construct(_InputIterator1 __first1, _InputIterator1 __last1,
4571        _InputIterator2 __first2, _InputIterator2 __last2,
4572        typename iterator_traits<_InputIterator1>::value_type* __result, _Compare __comp)
4573{
4574    typedef typename iterator_traits<_InputIterator1>::value_type value_type;
4575    __destruct_n __d(0);
4576    unique_ptr<value_type, __destruct_n&> __h(__result, __d);
4577    for (; true; ++__result)
4578    {
4579        if (__first1 == __last1)
4580        {
4581            for (; __first2 != __last2; ++__first2, ++__result, __d.__incr((value_type*)0))
4582                ::new (__result) value_type(_VSTD::move(*__first2));
4583            __h.release();
4584            return;
4585        }
4586        if (__first2 == __last2)
4587        {
4588            for (; __first1 != __last1; ++__first1, ++__result, __d.__incr((value_type*)0))
4589                ::new (__result) value_type(_VSTD::move(*__first1));
4590            __h.release();
4591            return;
4592        }
4593        if (__comp(*__first2, *__first1))
4594        {
4595            ::new (__result) value_type(_VSTD::move(*__first2));
4596            __d.__incr((value_type*)0);
4597            ++__first2;
4598        }
4599        else
4600        {
4601            ::new (__result) value_type(_VSTD::move(*__first1));
4602            __d.__incr((value_type*)0);
4603            ++__first1;
4604        }
4605    }
4606}
4607
4608template <class _Compare, class _InputIterator1, class _InputIterator2, class _OutputIterator>
4609void
4610__merge_move_assign(_InputIterator1 __first1, _InputIterator1 __last1,
4611        _InputIterator2 __first2, _InputIterator2 __last2,
4612        _OutputIterator __result, _Compare __comp)
4613{
4614    for (; __first1 != __last1; ++__result)
4615    {
4616        if (__first2 == __last2)
4617        {
4618            for (; __first1 != __last1; ++__first1, ++__result)
4619                *__result = _VSTD::move(*__first1);
4620            return;
4621        }
4622        if (__comp(*__first2, *__first1))
4623        {
4624            *__result = _VSTD::move(*__first2);
4625            ++__first2;
4626        }
4627        else
4628        {
4629            *__result = _VSTD::move(*__first1);
4630            ++__first1;
4631        }
4632    }
4633    for (; __first2 != __last2; ++__first2, ++__result)
4634        *__result = _VSTD::move(*__first2);
4635}
4636
4637template <class _Compare, class _RandomAccessIterator>
4638void
4639__stable_sort(_RandomAccessIterator __first, _RandomAccessIterator __last, _Compare __comp,
4640              typename iterator_traits<_RandomAccessIterator>::difference_type __len,
4641              typename iterator_traits<_RandomAccessIterator>::value_type* __buff, ptrdiff_t __buff_size);
4642
4643template <class _Compare, class _RandomAccessIterator>
4644void
4645__stable_sort_move(_RandomAccessIterator __first1, _RandomAccessIterator __last1, _Compare __comp,
4646                   typename iterator_traits<_RandomAccessIterator>::difference_type __len,
4647                   typename iterator_traits<_RandomAccessIterator>::value_type* __first2)
4648{
4649    typedef typename iterator_traits<_RandomAccessIterator>::value_type value_type;
4650    switch (__len)
4651    {
4652    case 0:
4653        return;
4654    case 1:
4655        ::new(__first2) value_type(_VSTD::move(*__first1));
4656        return;
4657    case 2:
4658        __destruct_n __d(0);
4659        unique_ptr<value_type, __destruct_n&> __h2(__first2, __d);
4660        if (__comp(*--__last1, *__first1))
4661        {
4662            ::new(__first2) value_type(_VSTD::move(*__last1));
4663            __d.__incr((value_type*)0);
4664            ++__first2;
4665            ::new(__first2) value_type(_VSTD::move(*__first1));
4666        }
4667        else
4668        {
4669            ::new(__first2) value_type(_VSTD::move(*__first1));
4670            __d.__incr((value_type*)0);
4671            ++__first2;
4672            ::new(__first2) value_type(_VSTD::move(*__last1));
4673        }
4674        __h2.release();
4675        return;
4676    }
4677    if (__len <= 8)
4678    {
4679        __insertion_sort_move<_Compare>(__first1, __last1, __first2, __comp);
4680        return;
4681    }
4682    typename iterator_traits<_RandomAccessIterator>::difference_type __l2 = __len / 2;
4683    _RandomAccessIterator __m = __first1 + __l2;
4684    __stable_sort<_Compare>(__first1, __m, __comp, __l2, __first2, __l2);
4685    __stable_sort<_Compare>(__m, __last1, __comp, __len - __l2, __first2 + __l2, __len - __l2);
4686    __merge_move_construct<_Compare>(__first1, __m, __m, __last1, __first2, __comp);
4687}
4688
4689template <class _Tp>
4690struct __stable_sort_switch
4691{
4692    static const unsigned value = 128*is_trivially_copy_assignable<_Tp>::value;
4693};
4694
4695template <class _Compare, class _RandomAccessIterator>
4696void
4697__stable_sort(_RandomAccessIterator __first, _RandomAccessIterator __last, _Compare __comp,
4698              typename iterator_traits<_RandomAccessIterator>::difference_type __len,
4699              typename iterator_traits<_RandomAccessIterator>::value_type* __buff, ptrdiff_t __buff_size)
4700{
4701    typedef typename iterator_traits<_RandomAccessIterator>::value_type value_type;
4702    typedef typename iterator_traits<_RandomAccessIterator>::difference_type difference_type;
4703    switch (__len)
4704    {
4705    case 0:
4706    case 1:
4707        return;
4708    case 2:
4709        if (__comp(*--__last, *__first))
4710            swap(*__first, *__last);
4711        return;
4712    }
4713    if (__len <= static_cast<difference_type>(__stable_sort_switch<value_type>::value))
4714    {
4715        __insertion_sort<_Compare>(__first, __last, __comp);
4716        return;
4717    }
4718    typename iterator_traits<_RandomAccessIterator>::difference_type __l2 = __len / 2;
4719    _RandomAccessIterator __m = __first + __l2;
4720    if (__len <= __buff_size)
4721    {
4722        __destruct_n __d(0);
4723        unique_ptr<value_type, __destruct_n&> __h2(__buff, __d);
4724        __stable_sort_move<_Compare>(__first, __m, __comp, __l2, __buff);
4725        __d.__set(__l2, (value_type*)0);
4726        __stable_sort_move<_Compare>(__m, __last, __comp, __len - __l2, __buff + __l2);
4727        __d.__set(__len, (value_type*)0);
4728        __merge_move_assign<_Compare>(__buff, __buff + __l2, __buff + __l2, __buff + __len, __first, __comp);
4729//         __merge<_Compare>(move_iterator<value_type*>(__buff),
4730//                           move_iterator<value_type*>(__buff + __l2),
4731//                           move_iterator<_RandomAccessIterator>(__buff + __l2),
4732//                           move_iterator<_RandomAccessIterator>(__buff + __len),
4733//                           __first, __comp);
4734        return;
4735    }
4736    __stable_sort<_Compare>(__first, __m, __comp, __l2, __buff, __buff_size);
4737    __stable_sort<_Compare>(__m, __last, __comp, __len - __l2, __buff, __buff_size);
4738    __inplace_merge<_Compare>(__first, __m, __last, __comp, __l2, __len - __l2, __buff, __buff_size);
4739}
4740
4741template <class _RandomAccessIterator, class _Compare>
4742inline _LIBCPP_INLINE_VISIBILITY
4743void
4744stable_sort(_RandomAccessIterator __first, _RandomAccessIterator __last, _Compare __comp)
4745{
4746    typedef typename iterator_traits<_RandomAccessIterator>::value_type value_type;
4747    typedef typename iterator_traits<_RandomAccessIterator>::difference_type difference_type;
4748    difference_type __len = __last - __first;
4749    pair<value_type*, ptrdiff_t> __buf(0, 0);
4750    unique_ptr<value_type, __return_temporary_buffer> __h;
4751    if (__len > static_cast<difference_type>(__stable_sort_switch<value_type>::value))
4752    {
4753        __buf = _VSTD::get_temporary_buffer<value_type>(__len);
4754        __h.reset(__buf.first);
4755    }
4756    typedef typename __comp_ref_type<_Compare>::type _Comp_ref;
4757    __stable_sort<_Comp_ref>(__first, __last, __comp, __len, __buf.first, __buf.second);
4758}
4759
4760template <class _RandomAccessIterator>
4761inline _LIBCPP_INLINE_VISIBILITY
4762void
4763stable_sort(_RandomAccessIterator __first, _RandomAccessIterator __last)
4764{
4765    _VSTD::stable_sort(__first, __last, __less<typename iterator_traits<_RandomAccessIterator>::value_type>());
4766}
4767
4768// is_heap_until
4769
4770template <class _RandomAccessIterator, class _Compare>
4771_LIBCPP_NODISCARD_EXT _LIBCPP_CONSTEXPR_AFTER_CXX17 _RandomAccessIterator
4772is_heap_until(_RandomAccessIterator __first, _RandomAccessIterator __last, _Compare __comp)
4773{
4774    typedef typename _VSTD::iterator_traits<_RandomAccessIterator>::difference_type difference_type;
4775    difference_type __len = __last - __first;
4776    difference_type __p = 0;
4777    difference_type __c = 1;
4778    _RandomAccessIterator __pp = __first;
4779    while (__c < __len)
4780    {
4781        _RandomAccessIterator __cp = __first + __c;
4782        if (__comp(*__pp, *__cp))
4783            return __cp;
4784        ++__c;
4785        ++__cp;
4786        if (__c == __len)
4787            return __last;
4788        if (__comp(*__pp, *__cp))
4789            return __cp;
4790        ++__p;
4791        ++__pp;
4792        __c = 2 * __p + 1;
4793    }
4794    return __last;
4795}
4796
4797template<class _RandomAccessIterator>
4798_LIBCPP_NODISCARD_EXT inline
4799_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
4800_RandomAccessIterator
4801is_heap_until(_RandomAccessIterator __first, _RandomAccessIterator __last)
4802{
4803    return _VSTD::is_heap_until(__first, __last, __less<typename iterator_traits<_RandomAccessIterator>::value_type>());
4804}
4805
4806// is_heap
4807
4808template <class _RandomAccessIterator, class _Compare>
4809_LIBCPP_NODISCARD_EXT inline
4810_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
4811bool
4812is_heap(_RandomAccessIterator __first, _RandomAccessIterator __last, _Compare __comp)
4813{
4814    return _VSTD::is_heap_until(__first, __last, __comp) == __last;
4815}
4816
4817template<class _RandomAccessIterator>
4818_LIBCPP_NODISCARD_EXT inline
4819_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
4820bool
4821is_heap(_RandomAccessIterator __first, _RandomAccessIterator __last)
4822{
4823    return _VSTD::is_heap(__first, __last, __less<typename iterator_traits<_RandomAccessIterator>::value_type>());
4824}
4825
4826// push_heap
4827
4828template <class _Compare, class _RandomAccessIterator>
4829void
4830__sift_up(_RandomAccessIterator __first, _RandomAccessIterator __last, _Compare __comp,
4831          typename iterator_traits<_RandomAccessIterator>::difference_type __len)
4832{
4833    typedef typename iterator_traits<_RandomAccessIterator>::value_type value_type;
4834    if (__len > 1)
4835    {
4836        __len = (__len - 2) / 2;
4837        _RandomAccessIterator __ptr = __first + __len;
4838        if (__comp(*__ptr, *--__last))
4839        {
4840            value_type __t(_VSTD::move(*__last));
4841            do
4842            {
4843                *__last = _VSTD::move(*__ptr);
4844                __last = __ptr;
4845                if (__len == 0)
4846                    break;
4847                __len = (__len - 1) / 2;
4848                __ptr = __first + __len;
4849            } while (__comp(*__ptr, __t));
4850            *__last = _VSTD::move(__t);
4851        }
4852    }
4853}
4854
4855template <class _RandomAccessIterator, class _Compare>
4856inline _LIBCPP_INLINE_VISIBILITY
4857void
4858push_heap(_RandomAccessIterator __first, _RandomAccessIterator __last, _Compare __comp)
4859{
4860    typedef typename __comp_ref_type<_Compare>::type _Comp_ref;
4861    __sift_up<_Comp_ref>(__first, __last, __comp, __last - __first);
4862}
4863
4864template <class _RandomAccessIterator>
4865inline _LIBCPP_INLINE_VISIBILITY
4866void
4867push_heap(_RandomAccessIterator __first, _RandomAccessIterator __last)
4868{
4869    _VSTD::push_heap(__first, __last, __less<typename iterator_traits<_RandomAccessIterator>::value_type>());
4870}
4871
4872// pop_heap
4873
4874template <class _Compare, class _RandomAccessIterator>
4875void
4876__sift_down(_RandomAccessIterator __first, _RandomAccessIterator /*__last*/,
4877            _Compare __comp,
4878            typename iterator_traits<_RandomAccessIterator>::difference_type __len,
4879            _RandomAccessIterator __start)
4880{
4881    typedef typename iterator_traits<_RandomAccessIterator>::difference_type difference_type;
4882    typedef typename iterator_traits<_RandomAccessIterator>::value_type value_type;
4883    // left-child of __start is at 2 * __start + 1
4884    // right-child of __start is at 2 * __start + 2
4885    difference_type __child = __start - __first;
4886
4887    if (__len < 2 || (__len - 2) / 2 < __child)
4888        return;
4889
4890    __child = 2 * __child + 1;
4891    _RandomAccessIterator __child_i = __first + __child;
4892
4893    if ((__child + 1) < __len && __comp(*__child_i, *(__child_i + 1))) {
4894        // right-child exists and is greater than left-child
4895        ++__child_i;
4896        ++__child;
4897    }
4898
4899    // check if we are in heap-order
4900    if (__comp(*__child_i, *__start))
4901        // we are, __start is larger than it's largest child
4902        return;
4903
4904    value_type __top(_VSTD::move(*__start));
4905    do
4906    {
4907        // we are not in heap-order, swap the parent with it's largest child
4908        *__start = _VSTD::move(*__child_i);
4909        __start = __child_i;
4910
4911        if ((__len - 2) / 2 < __child)
4912            break;
4913
4914        // recompute the child based off of the updated parent
4915        __child = 2 * __child + 1;
4916        __child_i = __first + __child;
4917
4918        if ((__child + 1) < __len && __comp(*__child_i, *(__child_i + 1))) {
4919            // right-child exists and is greater than left-child
4920            ++__child_i;
4921            ++__child;
4922        }
4923
4924        // check if we are in heap-order
4925    } while (!__comp(*__child_i, __top));
4926    *__start = _VSTD::move(__top);
4927}
4928
4929template <class _Compare, class _RandomAccessIterator>
4930inline _LIBCPP_INLINE_VISIBILITY
4931void
4932__pop_heap(_RandomAccessIterator __first, _RandomAccessIterator __last, _Compare __comp,
4933           typename iterator_traits<_RandomAccessIterator>::difference_type __len)
4934{
4935    if (__len > 1)
4936    {
4937        swap(*__first, *--__last);
4938        __sift_down<_Compare>(__first, __last, __comp, __len - 1, __first);
4939    }
4940}
4941
4942template <class _RandomAccessIterator, class _Compare>
4943inline _LIBCPP_INLINE_VISIBILITY
4944void
4945pop_heap(_RandomAccessIterator __first, _RandomAccessIterator __last, _Compare __comp)
4946{
4947    typedef typename __comp_ref_type<_Compare>::type _Comp_ref;
4948    __pop_heap<_Comp_ref>(__first, __last, __comp, __last - __first);
4949}
4950
4951template <class _RandomAccessIterator>
4952inline _LIBCPP_INLINE_VISIBILITY
4953void
4954pop_heap(_RandomAccessIterator __first, _RandomAccessIterator __last)
4955{
4956    _VSTD::pop_heap(__first, __last, __less<typename iterator_traits<_RandomAccessIterator>::value_type>());
4957}
4958
4959// make_heap
4960
4961template <class _Compare, class _RandomAccessIterator>
4962void
4963__make_heap(_RandomAccessIterator __first, _RandomAccessIterator __last, _Compare __comp)
4964{
4965    typedef typename iterator_traits<_RandomAccessIterator>::difference_type difference_type;
4966    difference_type __n = __last - __first;
4967    if (__n > 1)
4968    {
4969        // start from the first parent, there is no need to consider children
4970        for (difference_type __start = (__n - 2) / 2; __start >= 0; --__start)
4971        {
4972            __sift_down<_Compare>(__first, __last, __comp, __n, __first + __start);
4973        }
4974    }
4975}
4976
4977template <class _RandomAccessIterator, class _Compare>
4978inline _LIBCPP_INLINE_VISIBILITY
4979void
4980make_heap(_RandomAccessIterator __first, _RandomAccessIterator __last, _Compare __comp)
4981{
4982    typedef typename __comp_ref_type<_Compare>::type _Comp_ref;
4983    __make_heap<_Comp_ref>(__first, __last, __comp);
4984}
4985
4986template <class _RandomAccessIterator>
4987inline _LIBCPP_INLINE_VISIBILITY
4988void
4989make_heap(_RandomAccessIterator __first, _RandomAccessIterator __last)
4990{
4991    _VSTD::make_heap(__first, __last, __less<typename iterator_traits<_RandomAccessIterator>::value_type>());
4992}
4993
4994// sort_heap
4995
4996template <class _Compare, class _RandomAccessIterator>
4997void
4998__sort_heap(_RandomAccessIterator __first, _RandomAccessIterator __last, _Compare __comp)
4999{
5000    typedef typename iterator_traits<_RandomAccessIterator>::difference_type difference_type;
5001    for (difference_type __n = __last - __first; __n > 1; --__last, --__n)
5002        __pop_heap<_Compare>(__first, __last, __comp, __n);
5003}
5004
5005template <class _RandomAccessIterator, class _Compare>
5006inline _LIBCPP_INLINE_VISIBILITY
5007void
5008sort_heap(_RandomAccessIterator __first, _RandomAccessIterator __last, _Compare __comp)
5009{
5010    typedef typename __comp_ref_type<_Compare>::type _Comp_ref;
5011    __sort_heap<_Comp_ref>(__first, __last, __comp);
5012}
5013
5014template <class _RandomAccessIterator>
5015inline _LIBCPP_INLINE_VISIBILITY
5016void
5017sort_heap(_RandomAccessIterator __first, _RandomAccessIterator __last)
5018{
5019    _VSTD::sort_heap(__first, __last, __less<typename iterator_traits<_RandomAccessIterator>::value_type>());
5020}
5021
5022// partial_sort
5023
5024template <class _Compare, class _RandomAccessIterator>
5025void
5026__partial_sort(_RandomAccessIterator __first, _RandomAccessIterator __middle, _RandomAccessIterator __last,
5027             _Compare __comp)
5028{
5029    __make_heap<_Compare>(__first, __middle, __comp);
5030    typename iterator_traits<_RandomAccessIterator>::difference_type __len = __middle - __first;
5031    for (_RandomAccessIterator __i = __middle; __i != __last; ++__i)
5032    {
5033        if (__comp(*__i, *__first))
5034        {
5035            swap(*__i, *__first);
5036            __sift_down<_Compare>(__first, __middle, __comp, __len, __first);
5037        }
5038    }
5039    __sort_heap<_Compare>(__first, __middle, __comp);
5040}
5041
5042template <class _RandomAccessIterator, class _Compare>
5043inline _LIBCPP_INLINE_VISIBILITY
5044void
5045partial_sort(_RandomAccessIterator __first, _RandomAccessIterator __middle, _RandomAccessIterator __last,
5046             _Compare __comp)
5047{
5048    typedef typename __comp_ref_type<_Compare>::type _Comp_ref;
5049    __partial_sort<_Comp_ref>(__first, __middle, __last, __comp);
5050}
5051
5052template <class _RandomAccessIterator>
5053inline _LIBCPP_INLINE_VISIBILITY
5054void
5055partial_sort(_RandomAccessIterator __first, _RandomAccessIterator __middle, _RandomAccessIterator __last)
5056{
5057    _VSTD::partial_sort(__first, __middle, __last,
5058                       __less<typename iterator_traits<_RandomAccessIterator>::value_type>());
5059}
5060
5061// partial_sort_copy
5062
5063template <class _Compare, class _InputIterator, class _RandomAccessIterator>
5064_RandomAccessIterator
5065__partial_sort_copy(_InputIterator __first, _InputIterator __last,
5066                    _RandomAccessIterator __result_first, _RandomAccessIterator __result_last, _Compare __comp)
5067{
5068    _RandomAccessIterator __r = __result_first;
5069    if (__r != __result_last)
5070    {
5071        for (; __first != __last && __r != __result_last; (void) ++__first, ++__r)
5072            *__r = *__first;
5073        __make_heap<_Compare>(__result_first, __r, __comp);
5074        typename iterator_traits<_RandomAccessIterator>::difference_type __len = __r - __result_first;
5075        for (; __first != __last; ++__first)
5076            if (__comp(*__first, *__result_first))
5077            {
5078                *__result_first = *__first;
5079                __sift_down<_Compare>(__result_first, __r, __comp, __len, __result_first);
5080            }
5081        __sort_heap<_Compare>(__result_first, __r, __comp);
5082    }
5083    return __r;
5084}
5085
5086template <class _InputIterator, class _RandomAccessIterator, class _Compare>
5087inline _LIBCPP_INLINE_VISIBILITY
5088_RandomAccessIterator
5089partial_sort_copy(_InputIterator __first, _InputIterator __last,
5090                  _RandomAccessIterator __result_first, _RandomAccessIterator __result_last, _Compare __comp)
5091{
5092    typedef typename __comp_ref_type<_Compare>::type _Comp_ref;
5093    return __partial_sort_copy<_Comp_ref>(__first, __last, __result_first, __result_last, __comp);
5094}
5095
5096template <class _InputIterator, class _RandomAccessIterator>
5097inline _LIBCPP_INLINE_VISIBILITY
5098_RandomAccessIterator
5099partial_sort_copy(_InputIterator __first, _InputIterator __last,
5100                  _RandomAccessIterator __result_first, _RandomAccessIterator __result_last)
5101{
5102    return _VSTD::partial_sort_copy(__first, __last, __result_first, __result_last,
5103                                   __less<typename iterator_traits<_RandomAccessIterator>::value_type>());
5104}
5105
5106// nth_element
5107
5108template <class _Compare, class _RandomAccessIterator>
5109void
5110__nth_element(_RandomAccessIterator __first, _RandomAccessIterator __nth, _RandomAccessIterator __last, _Compare __comp)
5111{
5112    // _Compare is known to be a reference type
5113    typedef typename iterator_traits<_RandomAccessIterator>::difference_type difference_type;
5114    const difference_type __limit = 7;
5115    while (true)
5116    {
5117    __restart:
5118        if (__nth == __last)
5119            return;
5120        difference_type __len = __last - __first;
5121        switch (__len)
5122        {
5123        case 0:
5124        case 1:
5125            return;
5126        case 2:
5127            if (__comp(*--__last, *__first))
5128                swap(*__first, *__last);
5129            return;
5130        case 3:
5131            {
5132            _RandomAccessIterator __m = __first;
5133            _VSTD::__sort3<_Compare>(__first, ++__m, --__last, __comp);
5134            return;
5135            }
5136        }
5137        if (__len <= __limit)
5138        {
5139            __selection_sort<_Compare>(__first, __last, __comp);
5140            return;
5141        }
5142        // __len > __limit >= 3
5143        _RandomAccessIterator __m = __first + __len/2;
5144        _RandomAccessIterator __lm1 = __last;
5145        unsigned __n_swaps = _VSTD::__sort3<_Compare>(__first, __m, --__lm1, __comp);
5146        // *__m is median
5147        // partition [__first, __m) < *__m and *__m <= [__m, __last)
5148        // (this inhibits tossing elements equivalent to __m around unnecessarily)
5149        _RandomAccessIterator __i = __first;
5150        _RandomAccessIterator __j = __lm1;
5151        // j points beyond range to be tested, *__lm1 is known to be <= *__m
5152        // The search going up is known to be guarded but the search coming down isn't.
5153        // Prime the downward search with a guard.
5154        if (!__comp(*__i, *__m))  // if *__first == *__m
5155        {
5156            // *__first == *__m, *__first doesn't go in first part
5157            // manually guard downward moving __j against __i
5158            while (true)
5159            {
5160                if (__i == --__j)
5161                {
5162                    // *__first == *__m, *__m <= all other elements
5163                    // Parition instead into [__first, __i) == *__first and *__first < [__i, __last)
5164                    ++__i;  // __first + 1
5165                    __j = __last;
5166                    if (!__comp(*__first, *--__j))  // we need a guard if *__first == *(__last-1)
5167                    {
5168                        while (true)
5169                        {
5170                            if (__i == __j)
5171                                return;  // [__first, __last) all equivalent elements
5172                            if (__comp(*__first, *__i))
5173                            {
5174                                swap(*__i, *__j);
5175                                ++__n_swaps;
5176                                ++__i;
5177                                break;
5178                            }
5179                            ++__i;
5180                        }
5181                    }
5182                    // [__first, __i) == *__first and *__first < [__j, __last) and __j == __last - 1
5183                    if (__i == __j)
5184                        return;
5185                    while (true)
5186                    {
5187                        while (!__comp(*__first, *__i))
5188                            ++__i;
5189                        while (__comp(*__first, *--__j))
5190                            ;
5191                        if (__i >= __j)
5192                            break;
5193                        swap(*__i, *__j);
5194                        ++__n_swaps;
5195                        ++__i;
5196                    }
5197                    // [__first, __i) == *__first and *__first < [__i, __last)
5198                    // The first part is sorted,
5199                    if (__nth < __i)
5200                        return;
5201                    // __nth_element the secod part
5202                    // __nth_element<_Compare>(__i, __nth, __last, __comp);
5203                    __first = __i;
5204                    goto __restart;
5205                }
5206                if (__comp(*__j, *__m))
5207                {
5208                    swap(*__i, *__j);
5209                    ++__n_swaps;
5210                    break;  // found guard for downward moving __j, now use unguarded partition
5211                }
5212            }
5213        }
5214        ++__i;
5215        // j points beyond range to be tested, *__lm1 is known to be <= *__m
5216        // if not yet partitioned...
5217        if (__i < __j)
5218        {
5219            // known that *(__i - 1) < *__m
5220            while (true)
5221            {
5222                // __m still guards upward moving __i
5223                while (__comp(*__i, *__m))
5224                    ++__i;
5225                // It is now known that a guard exists for downward moving __j
5226                while (!__comp(*--__j, *__m))
5227                    ;
5228                if (__i >= __j)
5229                    break;
5230                swap(*__i, *__j);
5231                ++__n_swaps;
5232                // It is known that __m != __j
5233                // If __m just moved, follow it
5234                if (__m == __i)
5235                    __m = __j;
5236                ++__i;
5237            }
5238        }
5239        // [__first, __i) < *__m and *__m <= [__i, __last)
5240        if (__i != __m && __comp(*__m, *__i))
5241        {
5242            swap(*__i, *__m);
5243            ++__n_swaps;
5244        }
5245        // [__first, __i) < *__i and *__i <= [__i+1, __last)
5246        if (__nth == __i)
5247            return;
5248        if (__n_swaps == 0)
5249        {
5250            // We were given a perfectly partitioned sequence.  Coincidence?
5251            if (__nth < __i)
5252            {
5253                // Check for [__first, __i) already sorted
5254                __j = __m = __first;
5255                while (++__j != __i)
5256                {
5257                    if (__comp(*__j, *__m))
5258                        // not yet sorted, so sort
5259                        goto not_sorted;
5260                    __m = __j;
5261                }
5262                // [__first, __i) sorted
5263                return;
5264            }
5265            else
5266            {
5267                // Check for [__i, __last) already sorted
5268                __j = __m = __i;
5269                while (++__j != __last)
5270                {
5271                    if (__comp(*__j, *__m))
5272                        // not yet sorted, so sort
5273                        goto not_sorted;
5274                    __m = __j;
5275                }
5276                // [__i, __last) sorted
5277                return;
5278            }
5279        }
5280not_sorted:
5281        // __nth_element on range containing __nth
5282        if (__nth < __i)
5283        {
5284            // __nth_element<_Compare>(__first, __nth, __i, __comp);
5285            __last = __i;
5286        }
5287        else
5288        {
5289            // __nth_element<_Compare>(__i+1, __nth, __last, __comp);
5290            __first = ++__i;
5291        }
5292    }
5293}
5294
5295template <class _RandomAccessIterator, class _Compare>
5296inline _LIBCPP_INLINE_VISIBILITY
5297void
5298nth_element(_RandomAccessIterator __first, _RandomAccessIterator __nth, _RandomAccessIterator __last, _Compare __comp)
5299{
5300    typedef typename __comp_ref_type<_Compare>::type _Comp_ref;
5301    __nth_element<_Comp_ref>(__first, __nth, __last, __comp);
5302}
5303
5304template <class _RandomAccessIterator>
5305inline _LIBCPP_INLINE_VISIBILITY
5306void
5307nth_element(_RandomAccessIterator __first, _RandomAccessIterator __nth, _RandomAccessIterator __last)
5308{
5309    _VSTD::nth_element(__first, __nth, __last, __less<typename iterator_traits<_RandomAccessIterator>::value_type>());
5310}
5311
5312// includes
5313
5314template <class _Compare, class _InputIterator1, class _InputIterator2>
5315_LIBCPP_CONSTEXPR_AFTER_CXX17 bool
5316__includes(_InputIterator1 __first1, _InputIterator1 __last1, _InputIterator2 __first2, _InputIterator2 __last2,
5317           _Compare __comp)
5318{
5319    for (; __first2 != __last2; ++__first1)
5320    {
5321        if (__first1 == __last1 || __comp(*__first2, *__first1))
5322            return false;
5323        if (!__comp(*__first1, *__first2))
5324            ++__first2;
5325    }
5326    return true;
5327}
5328
5329template <class _InputIterator1, class _InputIterator2, class _Compare>
5330_LIBCPP_NODISCARD_EXT inline
5331_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
5332bool
5333includes(_InputIterator1 __first1, _InputIterator1 __last1, _InputIterator2 __first2, _InputIterator2 __last2,
5334         _Compare __comp)
5335{
5336    typedef typename __comp_ref_type<_Compare>::type _Comp_ref;
5337    return __includes<_Comp_ref>(__first1, __last1, __first2, __last2, __comp);
5338}
5339
5340template <class _InputIterator1, class _InputIterator2>
5341_LIBCPP_NODISCARD_EXT inline
5342_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
5343bool
5344includes(_InputIterator1 __first1, _InputIterator1 __last1, _InputIterator2 __first2, _InputIterator2 __last2)
5345{
5346    return _VSTD::includes(__first1, __last1, __first2, __last2,
5347                          __less<typename iterator_traits<_InputIterator1>::value_type,
5348                                 typename iterator_traits<_InputIterator2>::value_type>());
5349}
5350
5351// set_union
5352
5353template <class _Compare, class _InputIterator1, class _InputIterator2, class _OutputIterator>
5354_OutputIterator
5355__set_union(_InputIterator1 __first1, _InputIterator1 __last1,
5356            _InputIterator2 __first2, _InputIterator2 __last2, _OutputIterator __result, _Compare __comp)
5357{
5358    for (; __first1 != __last1; ++__result)
5359    {
5360        if (__first2 == __last2)
5361            return _VSTD::copy(__first1, __last1, __result);
5362        if (__comp(*__first2, *__first1))
5363        {
5364            *__result = *__first2;
5365            ++__first2;
5366        }
5367        else
5368        {
5369            if (!__comp(*__first1, *__first2))
5370                ++__first2;
5371            *__result = *__first1;
5372            ++__first1;
5373        }
5374    }
5375    return _VSTD::copy(__first2, __last2, __result);
5376}
5377
5378template <class _InputIterator1, class _InputIterator2, class _OutputIterator, class _Compare>
5379inline _LIBCPP_INLINE_VISIBILITY
5380_OutputIterator
5381set_union(_InputIterator1 __first1, _InputIterator1 __last1,
5382          _InputIterator2 __first2, _InputIterator2 __last2, _OutputIterator __result, _Compare __comp)
5383{
5384    typedef typename __comp_ref_type<_Compare>::type _Comp_ref;
5385    return __set_union<_Comp_ref>(__first1, __last1, __first2, __last2, __result, __comp);
5386}
5387
5388template <class _InputIterator1, class _InputIterator2, class _OutputIterator>
5389inline _LIBCPP_INLINE_VISIBILITY
5390_OutputIterator
5391set_union(_InputIterator1 __first1, _InputIterator1 __last1,
5392          _InputIterator2 __first2, _InputIterator2 __last2, _OutputIterator __result)
5393{
5394    return _VSTD::set_union(__first1, __last1, __first2, __last2, __result,
5395                          __less<typename iterator_traits<_InputIterator1>::value_type,
5396                                 typename iterator_traits<_InputIterator2>::value_type>());
5397}
5398
5399// set_intersection
5400
5401template <class _Compare, class _InputIterator1, class _InputIterator2, class _OutputIterator>
5402_LIBCPP_CONSTEXPR_AFTER_CXX17 _OutputIterator
5403__set_intersection(_InputIterator1 __first1, _InputIterator1 __last1,
5404                   _InputIterator2 __first2, _InputIterator2 __last2, _OutputIterator __result, _Compare __comp)
5405{
5406    while (__first1 != __last1 && __first2 != __last2)
5407    {
5408        if (__comp(*__first1, *__first2))
5409            ++__first1;
5410        else
5411        {
5412            if (!__comp(*__first2, *__first1))
5413            {
5414                *__result = *__first1;
5415                ++__result;
5416                ++__first1;
5417            }
5418            ++__first2;
5419        }
5420    }
5421    return __result;
5422}
5423
5424template <class _InputIterator1, class _InputIterator2, class _OutputIterator, class _Compare>
5425inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
5426_OutputIterator
5427set_intersection(_InputIterator1 __first1, _InputIterator1 __last1,
5428                 _InputIterator2 __first2, _InputIterator2 __last2, _OutputIterator __result, _Compare __comp)
5429{
5430    typedef typename __comp_ref_type<_Compare>::type _Comp_ref;
5431    return __set_intersection<_Comp_ref>(__first1, __last1, __first2, __last2, __result, __comp);
5432}
5433
5434template <class _InputIterator1, class _InputIterator2, class _OutputIterator>
5435inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
5436_OutputIterator
5437set_intersection(_InputIterator1 __first1, _InputIterator1 __last1,
5438                 _InputIterator2 __first2, _InputIterator2 __last2, _OutputIterator __result)
5439{
5440    return _VSTD::set_intersection(__first1, __last1, __first2, __last2, __result,
5441                                  __less<typename iterator_traits<_InputIterator1>::value_type,
5442                                         typename iterator_traits<_InputIterator2>::value_type>());
5443}
5444
5445// set_difference
5446
5447template <class _Compare, class _InputIterator1, class _InputIterator2, class _OutputIterator>
5448_OutputIterator
5449__set_difference(_InputIterator1 __first1, _InputIterator1 __last1,
5450                 _InputIterator2 __first2, _InputIterator2 __last2, _OutputIterator __result, _Compare __comp)
5451{
5452    while (__first1 != __last1)
5453    {
5454        if (__first2 == __last2)
5455            return _VSTD::copy(__first1, __last1, __result);
5456        if (__comp(*__first1, *__first2))
5457        {
5458            *__result = *__first1;
5459            ++__result;
5460            ++__first1;
5461        }
5462        else
5463        {
5464            if (!__comp(*__first2, *__first1))
5465                ++__first1;
5466            ++__first2;
5467        }
5468    }
5469    return __result;
5470}
5471
5472template <class _InputIterator1, class _InputIterator2, class _OutputIterator, class _Compare>
5473inline _LIBCPP_INLINE_VISIBILITY
5474_OutputIterator
5475set_difference(_InputIterator1 __first1, _InputIterator1 __last1,
5476               _InputIterator2 __first2, _InputIterator2 __last2, _OutputIterator __result, _Compare __comp)
5477{
5478    typedef typename __comp_ref_type<_Compare>::type _Comp_ref;
5479    return __set_difference<_Comp_ref>(__first1, __last1, __first2, __last2, __result, __comp);
5480}
5481
5482template <class _InputIterator1, class _InputIterator2, class _OutputIterator>
5483inline _LIBCPP_INLINE_VISIBILITY
5484_OutputIterator
5485set_difference(_InputIterator1 __first1, _InputIterator1 __last1,
5486               _InputIterator2 __first2, _InputIterator2 __last2, _OutputIterator __result)
5487{
5488    return _VSTD::set_difference(__first1, __last1, __first2, __last2, __result,
5489                                __less<typename iterator_traits<_InputIterator1>::value_type,
5490                                       typename iterator_traits<_InputIterator2>::value_type>());
5491}
5492
5493// set_symmetric_difference
5494
5495template <class _Compare, class _InputIterator1, class _InputIterator2, class _OutputIterator>
5496_OutputIterator
5497__set_symmetric_difference(_InputIterator1 __first1, _InputIterator1 __last1,
5498                           _InputIterator2 __first2, _InputIterator2 __last2, _OutputIterator __result, _Compare __comp)
5499{
5500    while (__first1 != __last1)
5501    {
5502        if (__first2 == __last2)
5503            return _VSTD::copy(__first1, __last1, __result);
5504        if (__comp(*__first1, *__first2))
5505        {
5506            *__result = *__first1;
5507            ++__result;
5508            ++__first1;
5509        }
5510        else
5511        {
5512            if (__comp(*__first2, *__first1))
5513            {
5514                *__result = *__first2;
5515                ++__result;
5516            }
5517            else
5518                ++__first1;
5519            ++__first2;
5520        }
5521    }
5522    return _VSTD::copy(__first2, __last2, __result);
5523}
5524
5525template <class _InputIterator1, class _InputIterator2, class _OutputIterator, class _Compare>
5526inline _LIBCPP_INLINE_VISIBILITY
5527_OutputIterator
5528set_symmetric_difference(_InputIterator1 __first1, _InputIterator1 __last1,
5529                         _InputIterator2 __first2, _InputIterator2 __last2, _OutputIterator __result, _Compare __comp)
5530{
5531    typedef typename __comp_ref_type<_Compare>::type _Comp_ref;
5532    return __set_symmetric_difference<_Comp_ref>(__first1, __last1, __first2, __last2, __result, __comp);
5533}
5534
5535template <class _InputIterator1, class _InputIterator2, class _OutputIterator>
5536inline _LIBCPP_INLINE_VISIBILITY
5537_OutputIterator
5538set_symmetric_difference(_InputIterator1 __first1, _InputIterator1 __last1,
5539                         _InputIterator2 __first2, _InputIterator2 __last2, _OutputIterator __result)
5540{
5541    return _VSTD::set_symmetric_difference(__first1, __last1, __first2, __last2, __result,
5542                                          __less<typename iterator_traits<_InputIterator1>::value_type,
5543                                                 typename iterator_traits<_InputIterator2>::value_type>());
5544}
5545
5546// lexicographical_compare
5547
5548template <class _Compare, class _InputIterator1, class _InputIterator2>
5549_LIBCPP_CONSTEXPR_AFTER_CXX17 bool
5550__lexicographical_compare(_InputIterator1 __first1, _InputIterator1 __last1,
5551                          _InputIterator2 __first2, _InputIterator2 __last2, _Compare __comp)
5552{
5553    for (; __first2 != __last2; ++__first1, (void) ++__first2)
5554    {
5555        if (__first1 == __last1 || __comp(*__first1, *__first2))
5556            return true;
5557        if (__comp(*__first2, *__first1))
5558            return false;
5559    }
5560    return false;
5561}
5562
5563template <class _InputIterator1, class _InputIterator2, class _Compare>
5564_LIBCPP_NODISCARD_EXT inline
5565_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
5566bool
5567lexicographical_compare(_InputIterator1 __first1, _InputIterator1 __last1,
5568                        _InputIterator2 __first2, _InputIterator2 __last2, _Compare __comp)
5569{
5570    typedef typename __comp_ref_type<_Compare>::type _Comp_ref;
5571    return __lexicographical_compare<_Comp_ref>(__first1, __last1, __first2, __last2, __comp);
5572}
5573
5574template <class _InputIterator1, class _InputIterator2>
5575_LIBCPP_NODISCARD_EXT inline
5576_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
5577bool
5578lexicographical_compare(_InputIterator1 __first1, _InputIterator1 __last1,
5579                        _InputIterator2 __first2, _InputIterator2 __last2)
5580{
5581    return _VSTD::lexicographical_compare(__first1, __last1, __first2, __last2,
5582                                         __less<typename iterator_traits<_InputIterator1>::value_type,
5583                                                typename iterator_traits<_InputIterator2>::value_type>());
5584}
5585
5586// next_permutation
5587
5588template <class _Compare, class _BidirectionalIterator>
5589bool
5590__next_permutation(_BidirectionalIterator __first, _BidirectionalIterator __last, _Compare __comp)
5591{
5592    _BidirectionalIterator __i = __last;
5593    if (__first == __last || __first == --__i)
5594        return false;
5595    while (true)
5596    {
5597        _BidirectionalIterator __ip1 = __i;
5598        if (__comp(*--__i, *__ip1))
5599        {
5600            _BidirectionalIterator __j = __last;
5601            while (!__comp(*__i, *--__j))
5602                ;
5603            swap(*__i, *__j);
5604            _VSTD::reverse(__ip1, __last);
5605            return true;
5606        }
5607        if (__i == __first)
5608        {
5609            _VSTD::reverse(__first, __last);
5610            return false;
5611        }
5612    }
5613}
5614
5615template <class _BidirectionalIterator, class _Compare>
5616inline _LIBCPP_INLINE_VISIBILITY
5617bool
5618next_permutation(_BidirectionalIterator __first, _BidirectionalIterator __last, _Compare __comp)
5619{
5620    typedef typename __comp_ref_type<_Compare>::type _Comp_ref;
5621    return __next_permutation<_Comp_ref>(__first, __last, __comp);
5622}
5623
5624template <class _BidirectionalIterator>
5625inline _LIBCPP_INLINE_VISIBILITY
5626bool
5627next_permutation(_BidirectionalIterator __first, _BidirectionalIterator __last)
5628{
5629    return _VSTD::next_permutation(__first, __last,
5630                                  __less<typename iterator_traits<_BidirectionalIterator>::value_type>());
5631}
5632
5633// prev_permutation
5634
5635template <class _Compare, class _BidirectionalIterator>
5636bool
5637__prev_permutation(_BidirectionalIterator __first, _BidirectionalIterator __last, _Compare __comp)
5638{
5639    _BidirectionalIterator __i = __last;
5640    if (__first == __last || __first == --__i)
5641        return false;
5642    while (true)
5643    {
5644        _BidirectionalIterator __ip1 = __i;
5645        if (__comp(*__ip1, *--__i))
5646        {
5647            _BidirectionalIterator __j = __last;
5648            while (!__comp(*--__j, *__i))
5649                ;
5650            swap(*__i, *__j);
5651            _VSTD::reverse(__ip1, __last);
5652            return true;
5653        }
5654        if (__i == __first)
5655        {
5656            _VSTD::reverse(__first, __last);
5657            return false;
5658        }
5659    }
5660}
5661
5662template <class _BidirectionalIterator, class _Compare>
5663inline _LIBCPP_INLINE_VISIBILITY
5664bool
5665prev_permutation(_BidirectionalIterator __first, _BidirectionalIterator __last, _Compare __comp)
5666{
5667    typedef typename __comp_ref_type<_Compare>::type _Comp_ref;
5668    return __prev_permutation<_Comp_ref>(__first, __last, __comp);
5669}
5670
5671template <class _BidirectionalIterator>
5672inline _LIBCPP_INLINE_VISIBILITY
5673bool
5674prev_permutation(_BidirectionalIterator __first, _BidirectionalIterator __last)
5675{
5676    return _VSTD::prev_permutation(__first, __last,
5677                                  __less<typename iterator_traits<_BidirectionalIterator>::value_type>());
5678}
5679
5680_LIBCPP_END_NAMESPACE_STD
5681
5682_LIBCPP_POP_MACROS
5683
5684#endif  // _LIBCPP_ALGORITHM
5685