69 lines
1.6 KiB
C++
69 lines
1.6 KiB
C++
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//===----------------------------------------------------------------------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is dual licensed under the MIT and the University of Illinois Open
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// Source Licenses. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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// <algorithm>
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// template<BidirectionalIterator Iter, StrictWeakOrder<auto, Iter::value_type> Compare>
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// requires ShuffleIterator<Iter>
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// && CopyConstructible<Compare>
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// bool
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// next_permutation(Iter first, Iter last, Compare comp);
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#include <algorithm>
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#include <functional>
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#include <cassert>
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#include "test_iterators.h"
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#include <cstdio>
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int factorial(int x)
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{
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int r = 1;
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for (; x; --x)
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r *= x;
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return r;
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}
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template <class Iter>
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void
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test()
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{
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typedef std::greater<int> C;
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int ia[] = {6, 5, 4, 3, 2, 1};
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const int sa = sizeof(ia)/sizeof(ia[0]);
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int prev[sa];
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for (int e = 0; e <= sa; ++e)
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{
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int count = 0;
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bool x;
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do
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{
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std::copy(ia, ia+e, prev);
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x = std::next_permutation(Iter(ia), Iter(ia+e), C());
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if (e > 1)
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{
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if (x)
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assert(std::lexicographical_compare(prev, prev+e, ia, ia+e, C()));
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else
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assert(std::lexicographical_compare(ia, ia+e, prev, prev+e, C()));
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}
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++count;
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} while (x);
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assert(count == factorial(e));
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}
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}
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int main()
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{
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test<bidirectional_iterator<int*> >();
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test<random_access_iterator<int*> >();
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test<int*>();
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}
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