1bc8d3f97eb5c958007f2713238472e0c1c8fe02Howard Hinnant//===----------------------------------------------------------------------===// 2bc8d3f97eb5c958007f2713238472e0c1c8fe02Howard Hinnant// 3f5256e16dfc425c1d466f6308d4026d529ce9e0bHoward Hinnant// The LLVM Compiler Infrastructure 4bc8d3f97eb5c958007f2713238472e0c1c8fe02Howard Hinnant// 5b64f8b07c104c6cc986570ac8ee0ed16a9f23976Howard Hinnant// This file is dual licensed under the MIT and the University of Illinois Open 6b64f8b07c104c6cc986570ac8ee0ed16a9f23976Howard Hinnant// Source Licenses. See LICENSE.TXT for details. 7bc8d3f97eb5c958007f2713238472e0c1c8fe02Howard Hinnant// 8bc8d3f97eb5c958007f2713238472e0c1c8fe02Howard Hinnant//===----------------------------------------------------------------------===// 9bc8d3f97eb5c958007f2713238472e0c1c8fe02Howard Hinnant 10bc8d3f97eb5c958007f2713238472e0c1c8fe02Howard Hinnant// <algorithm> 11bc8d3f97eb5c958007f2713238472e0c1c8fe02Howard Hinnant 12eb564e76cc3904d811c981a50ecce0659f444cc9Howard Hinnant// template<BidirectionalIterator Iter> 13eb564e76cc3904d811c981a50ecce0659f444cc9Howard Hinnant// requires ShuffleIterator<Iter> 14eb564e76cc3904d811c981a50ecce0659f444cc9Howard Hinnant// && LessThanComparable<Iter::value_type> 15bc8d3f97eb5c958007f2713238472e0c1c8fe02Howard Hinnant// bool 16bc8d3f97eb5c958007f2713238472e0c1c8fe02Howard Hinnant// prev_permutation(Iter first, Iter last); 17bc8d3f97eb5c958007f2713238472e0c1c8fe02Howard Hinnant 18bc8d3f97eb5c958007f2713238472e0c1c8fe02Howard Hinnant#include <algorithm> 19bc8d3f97eb5c958007f2713238472e0c1c8fe02Howard Hinnant#include <cassert> 20bc8d3f97eb5c958007f2713238472e0c1c8fe02Howard Hinnant 2183e2c4d877fe2d7793868b1c6a5d9525a7c4d431Marshall Clow#include "test_iterators.h" 22bc8d3f97eb5c958007f2713238472e0c1c8fe02Howard Hinnant 23bc8d3f97eb5c958007f2713238472e0c1c8fe02Howard Hinnant#include <cstdio> 24bc8d3f97eb5c958007f2713238472e0c1c8fe02Howard Hinnant 25bc8d3f97eb5c958007f2713238472e0c1c8fe02Howard Hinnantint factorial(int x) 26bc8d3f97eb5c958007f2713238472e0c1c8fe02Howard Hinnant{ 27bc8d3f97eb5c958007f2713238472e0c1c8fe02Howard Hinnant int r = 1; 28bc8d3f97eb5c958007f2713238472e0c1c8fe02Howard Hinnant for (; x; --x) 29bc8d3f97eb5c958007f2713238472e0c1c8fe02Howard Hinnant r *= x; 30bc8d3f97eb5c958007f2713238472e0c1c8fe02Howard Hinnant return r; 31bc8d3f97eb5c958007f2713238472e0c1c8fe02Howard Hinnant} 32bc8d3f97eb5c958007f2713238472e0c1c8fe02Howard Hinnant 33bc8d3f97eb5c958007f2713238472e0c1c8fe02Howard Hinnanttemplate <class Iter> 34bc8d3f97eb5c958007f2713238472e0c1c8fe02Howard Hinnantvoid 35bc8d3f97eb5c958007f2713238472e0c1c8fe02Howard Hinnanttest() 36bc8d3f97eb5c958007f2713238472e0c1c8fe02Howard Hinnant{ 37bc8d3f97eb5c958007f2713238472e0c1c8fe02Howard Hinnant int ia[] = {6, 5, 4, 3, 2, 1}; 38bc8d3f97eb5c958007f2713238472e0c1c8fe02Howard Hinnant const int sa = sizeof(ia)/sizeof(ia[0]); 39bc8d3f97eb5c958007f2713238472e0c1c8fe02Howard Hinnant int prev[sa]; 40bc8d3f97eb5c958007f2713238472e0c1c8fe02Howard Hinnant for (int e = 0; e <= sa; ++e) 41bc8d3f97eb5c958007f2713238472e0c1c8fe02Howard Hinnant { 42bc8d3f97eb5c958007f2713238472e0c1c8fe02Howard Hinnant int count = 0; 43bc8d3f97eb5c958007f2713238472e0c1c8fe02Howard Hinnant bool x; 44bc8d3f97eb5c958007f2713238472e0c1c8fe02Howard Hinnant do 45bc8d3f97eb5c958007f2713238472e0c1c8fe02Howard Hinnant { 46bc8d3f97eb5c958007f2713238472e0c1c8fe02Howard Hinnant std::copy(ia, ia+e, prev); 47bc8d3f97eb5c958007f2713238472e0c1c8fe02Howard Hinnant x = std::prev_permutation(Iter(ia), Iter(ia+e)); 48bc8d3f97eb5c958007f2713238472e0c1c8fe02Howard Hinnant if (e > 1) 49bc8d3f97eb5c958007f2713238472e0c1c8fe02Howard Hinnant { 50bc8d3f97eb5c958007f2713238472e0c1c8fe02Howard Hinnant if (x) 51bc8d3f97eb5c958007f2713238472e0c1c8fe02Howard Hinnant assert(std::lexicographical_compare(ia, ia+e, prev, prev+e)); 52bc8d3f97eb5c958007f2713238472e0c1c8fe02Howard Hinnant else 53bc8d3f97eb5c958007f2713238472e0c1c8fe02Howard Hinnant assert(std::lexicographical_compare(prev, prev+e, ia, ia+e)); 54bc8d3f97eb5c958007f2713238472e0c1c8fe02Howard Hinnant } 55bc8d3f97eb5c958007f2713238472e0c1c8fe02Howard Hinnant ++count; 56bc8d3f97eb5c958007f2713238472e0c1c8fe02Howard Hinnant } while (x); 57bc8d3f97eb5c958007f2713238472e0c1c8fe02Howard Hinnant assert(count == factorial(e)); 58bc8d3f97eb5c958007f2713238472e0c1c8fe02Howard Hinnant } 59bc8d3f97eb5c958007f2713238472e0c1c8fe02Howard Hinnant} 60bc8d3f97eb5c958007f2713238472e0c1c8fe02Howard Hinnant 61bc8d3f97eb5c958007f2713238472e0c1c8fe02Howard Hinnantint main() 62bc8d3f97eb5c958007f2713238472e0c1c8fe02Howard Hinnant{ 63bc8d3f97eb5c958007f2713238472e0c1c8fe02Howard Hinnant test<bidirectional_iterator<int*> >(); 64bc8d3f97eb5c958007f2713238472e0c1c8fe02Howard Hinnant test<random_access_iterator<int*> >(); 65bc8d3f97eb5c958007f2713238472e0c1c8fe02Howard Hinnant test<int*>(); 66bc8d3f97eb5c958007f2713238472e0c1c8fe02Howard Hinnant} 67