naughtyfox
6 years ago
parent
8534f71eed
commit
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// Copyright (c) 2018, The Monero Project
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//
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// All rights reserved.
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//
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// Redistribution and use in source and binary forms, with or without modification, are
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// permitted provided that the following conditions are met:
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//
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// 1. Redistributions of source code must retain the above copyright notice, this list of
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// conditions and the following disclaimer.
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//
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// 2. Redistributions in binary form must reproduce the above copyright notice, this list
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// of conditions and the following disclaimer in the documentation and/or other
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// materials provided with the distribution.
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//
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// 3. Neither the name of the copyright holder nor the names of its contributors may be
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// used to endorse or promote products derived from this software without specific
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// prior written permission.
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//
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// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY
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// EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
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// MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
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// THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
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// STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
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// THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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//
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// Parts of this file are originally copyright (c) 2012-2013 The Cryptonote developers
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#include "combinator.h"
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namespace tools {
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uint64_t combinations_count(uint32_t k, uint32_t n)
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{
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if (k > n) {
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throw std::runtime_error("k must not be greater than n");
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}
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uint64_t c = 1;
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for (uint64_t i = 1; i <= k; ++i) {
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c *= n--;
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c /= i;
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}
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return c;
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}
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}
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@ -0,0 +1,96 @@
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// Copyright (c) 2018, The Monero Project
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//
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// All rights reserved.
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//
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// Redistribution and use in source and binary forms, with or without modification, are
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// permitted provided that the following conditions are met:
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//
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// 1. Redistributions of source code must retain the above copyright notice, this list of
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// conditions and the following disclaimer.
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//
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// 2. Redistributions in binary form must reproduce the above copyright notice, this list
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// of conditions and the following disclaimer in the documentation and/or other
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// materials provided with the distribution.
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//
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// 3. Neither the name of the copyright holder nor the names of its contributors may be
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// used to endorse or promote products derived from this software without specific
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// prior written permission.
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//
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// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY
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// EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
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// MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
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// THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
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// STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
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// THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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//
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// Parts of this file are originally copyright (c) 2012-2013 The Cryptonote developers
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#pragma once
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#include <iostream>
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#include <vector>
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namespace tools {
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uint64_t combinations_count(uint32_t k, uint32_t n);
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template<typename T>
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class Combinator {
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public:
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Combinator(const std::vector<T>& v) : origin(v) { }
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std::vector<std::vector<T>> combine(size_t k);
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private:
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void doCombine(size_t from, size_t k);
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std::vector<T> origin;
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std::vector<std::vector<T>> combinations;
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std::vector<size_t> current;
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};
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template<typename T>
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std::vector<std::vector<T>> Combinator<T>::combine(size_t k)
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{
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if (k > origin.size())
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{
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throw std::runtime_error("k must be smaller than elements number");
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}
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if (k == 0)
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{
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throw std::runtime_error("k must be greater than zero");
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}
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combinations.clear();
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doCombine(0, k);
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return combinations;
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}
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template<typename T>
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void Combinator<T>::doCombine(size_t from, size_t k)
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{
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current.push_back(0);
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for (size_t i = from; i <= origin.size() - k; ++i)
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{
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current.back() = i;
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if (k > 1) {
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doCombine(i + 1, k - 1);
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} else {
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std::vector<T> comb;
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for (auto ind: current) {
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comb.push_back(origin[ind]);
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}
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combinations.push_back(comb);
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}
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}
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current.pop_back();
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}
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} //namespace tools
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