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//===----------------------------------------------------------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
// <algorithm>
// template<RandomAccessIterator Iter, StrictWeakOrder<auto, Iter::value_type> Compare>
// requires ShuffleIterator<Iter>
// && CopyConstructible<Compare>
// void
// nth_element(Iter first, Iter nth, Iter last, Compare comp);
#include <algorithm>
#include <functional>
#include <vector>
#include <cassert>
#ifdef _LIBCPP_MOVE
#include <memory>
struct indirect_less
{
template <class P>
bool operator()(const P& x, const P& y)
{return *x < *y;}
};
#endif
void
test_one(unsigned N, unsigned M)
{
assert(N != 0);
assert(M < N);
int* array = new int[N];
for (int i = 0; i < N; ++i)
array[i] = i;
std::random_shuffle(array, array+N);
std::nth_element(array, array+M, array+N, std::greater<int>());
assert(array[M] == N-M-1);
delete [] array;
}
void
test(unsigned N)
{
test_one(N, 0);
test_one(N, 1);
test_one(N, 2);
test_one(N, 3);
test_one(N, N/2-1);
test_one(N, N/2);
test_one(N, N/2+1);
test_one(N, N-3);
test_one(N, N-2);
test_one(N, N-1);
}
int main()
{
int d = 0;
std::nth_element(&d, &d, &d);
assert(d == 0);
test(256);
test(257);
test(499);
test(500);
test(997);
test(1000);
test(1009);
#ifdef _LIBCPP_MOVE
{
std::vector<std::unique_ptr<int> > v(1000);
for (int i = 0; i < v.size(); ++i)
v[i].reset(new int(i));
std::nth_element(v.begin(), v.begin() + v.size()/2, v.end(), indirect_less());
assert(*v[v.size()/2] == v.size()/2);
}
#endif
}
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