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104 lines
2.8 KiB
C++
104 lines
2.8 KiB
C++
// Range v3 library
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//
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// Copyright Eric Niebler 2014-present
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//
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// Use, modification and distribution is subject to the
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// Boost Software License, Version 1.0. (See accompanying
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// file LICENSE_1_0.txt or copy at
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// http://www.boost.org/LICENSE_1_0.txt)
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//
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// Project home: https://github.com/ericniebler/range-v3
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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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#include <memory>
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#include <random>
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#include <algorithm>
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#include <range/v3/core.hpp>
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#include <range/v3/algorithm/nth_element.hpp>
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#include "../simple_test.hpp"
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#include "../test_utils.hpp"
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#include "../test_iterators.hpp"
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RANGES_DIAGNOSTIC_IGNORE_GLOBAL_CONSTRUCTORS
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RANGES_DIAGNOSTIC_IGNORE_SIGN_CONVERSION
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namespace
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{
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std::mt19937 gen;
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void
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test_one(unsigned N, unsigned M)
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{
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RANGES_ENSURE(N != 0);
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RANGES_ENSURE(M < N);
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std::unique_ptr<int[]> array{new int[N]};
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for (int i = 0; (unsigned)i < N; ++i)
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array[i] = i;
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std::shuffle(array.get(), array.get()+N, gen);
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CHECK(ranges::nth_element(array.get(), array.get()+M, array.get()+N) == array.get()+N);
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CHECK((unsigned)array[M] == M);
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std::shuffle(array.get(), array.get()+N, gen);
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CHECK(ranges::nth_element(::as_lvalue(ranges::make_subrange(array.get(), array.get()+N)), array.get()+M) == array.get()+N);
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CHECK((unsigned)array[M] == M);
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std::shuffle(array.get(), array.get()+N, gen);
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CHECK(ranges::nth_element(ranges::make_subrange(array.get(), array.get()+N), array.get()+M) == array.get()+N);
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CHECK((unsigned)array[M] == M);
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ranges::nth_element(array.get(), array.get()+N, array.get()+N); // first, last, end
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}
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void
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test(unsigned N)
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{
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test_one(N, 0);
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test_one(N, 1);
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test_one(N, 2);
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test_one(N, 3);
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test_one(N, N/2-1);
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test_one(N, N/2);
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test_one(N, N/2+1);
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test_one(N, N-3);
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test_one(N, N-2);
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test_one(N, N-1);
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}
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struct S
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{
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int i,j;
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};
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}
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int main()
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{
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int d = 0;
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ranges::nth_element(&d, &d, &d);
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CHECK(d == 0);
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test(256);
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test(257);
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test(499);
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test(500);
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test(997);
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test(1000);
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test(1009);
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// Works with projections?
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const int N = 257;
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const int M = 56;
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S ia[N];
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for(int i = 0; i < N; ++i)
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ia[i].i = ia[i].j = i;
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std::shuffle(ia, ia+N, gen);
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ranges::nth_element(ia, ia+M, std::less<int>(), &S::i);
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CHECK(ia[M].i == M);
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CHECK(ia[M].j == M);
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return test_result();
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}
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