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// Range v3 library
//
// Copyright Eric Niebler 2014-present
//
// Use, modification and distribution is subject to the
// Boost Software License, Version 1.0. (See accompanying
// file LICENSE_1_0.txt or copy at
// http://www.boost.org/LICENSE_1_0.txt)
//
// Project home: https://github.com/ericniebler/range-v3
//===----------------------------------------------------------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is dual licensed under the MIT and the University of Illinois Open
// Source Licenses. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#include <memory>
#include <random>
#include <algorithm>
#include <range/v3/core.hpp>
#include <range/v3/algorithm/nth_element.hpp>
#include "../simple_test.hpp"
#include "../test_utils.hpp"
#include "../test_iterators.hpp"
RANGES_DIAGNOSTIC_IGNORE_GLOBAL_CONSTRUCTORS
RANGES_DIAGNOSTIC_IGNORE_SIGN_CONVERSION
namespace
{
std::mt19937 gen;
void
test_one(unsigned N, unsigned M)
{
RANGES_ENSURE(N != 0);
RANGES_ENSURE(M < N);
std::unique_ptr<int[]> array{new int[N]};
for (int i = 0; (unsigned)i < N; ++i)
array[i] = i;
std::shuffle(array.get(), array.get()+N, gen);
CHECK(ranges::nth_element(array.get(), array.get()+M, array.get()+N) == array.get()+N);
CHECK((unsigned)array[M] == M);
std::shuffle(array.get(), array.get()+N, gen);
CHECK(ranges::nth_element(::as_lvalue(ranges::make_subrange(array.get(), array.get()+N)), array.get()+M) == array.get()+N);
CHECK((unsigned)array[M] == M);
std::shuffle(array.get(), array.get()+N, gen);
CHECK(ranges::nth_element(ranges::make_subrange(array.get(), array.get()+N), array.get()+M) == array.get()+N);
CHECK((unsigned)array[M] == M);
ranges::nth_element(array.get(), array.get()+N, array.get()+N); // first, last, end
}
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);
}
struct S
{
int i,j;
};
}
int main()
{
int d = 0;
ranges::nth_element(&d, &d, &d);
CHECK(d == 0);
test(256);
test(257);
test(499);
test(500);
test(997);
test(1000);
test(1009);
// Works with projections?
const int N = 257;
const int M = 56;
S ia[N];
for(int i = 0; i < N; ++i)
ia[i].i = ia[i].j = i;
std::shuffle(ia, ia+N, gen);
ranges::nth_element(ia, ia+M, std::less<int>(), &S::i);
CHECK(ia[M].i == M);
CHECK(ia[M].j == M);
return test_result();
}
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