kopia lustrzana https://github.com/vsamy/DiFipp
62 wiersze
2.3 KiB
C++
62 wiersze
2.3 KiB
C++
// Copyright (c) 2019, Vincent SAMY
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// All rights reserved.
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// Redistribution and use in source and binary forms, with or without
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// modification, are permitted provided that the following conditions are met:
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// 1. Redistributions of source code must retain the above copyright notice,
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// this list of conditions and the following disclaimer.
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// 2. Redistributions in binary form must reproduce the above copyright notice,
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// this list of conditions and the following disclaimer in the documentation
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// and/or other materials provided with the distribution.
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// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
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// ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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// WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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// DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
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// ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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// (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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// LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
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// ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
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// SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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// The views and conclusions contained in the software and documentation are those
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// of the authors and should not be interpreted as representing official policies,
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// either expressed or implied, of the FreeBSD Project.
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#pragma once
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#include <type_traits>
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namespace difi {
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// https://stackoverflow.com/questions/44718971/calculate-binomial-coffeficient-very-reliably
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template <typename T>
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constexpr T Binomial(int n, int k)
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{
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if (k > n)
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return T(0);
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else if (k == 0 || k == n)
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return T(1);
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else if (k == 1 || k == n - 1)
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return T(n);
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else if (2 * k < n)
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return Binomial<T>(n - 1, k - 1) * n / k;
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else
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return Binomial<T>(n - 1, k) * n / (n - k);
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}
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template <typename T>
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constexpr T pow(T n, T k)
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{
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static_assert(std::is_integral<T>::value, "For integral values only, eitherwise, use std::pow");
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if (n == 0)
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return (k == 0) ? 1 : 0;
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else if (k == 0)
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return T(1);
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else
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return n * pow(n, k - 1);
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}
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} // namespace difi
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