90 lines
2.0 KiB
C++
90 lines
2.0 KiB
C++
#include "./math.h"
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#include <cassert>
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#include <cstdlib>
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/*!
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* \namespace MathUtilities
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* \brief Contains various mathematical functions.
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* \todo Move math.h and math.cpp to misc in v5.
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*/
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namespace MathUtilities {
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/*!
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* \brief Returns the digitsum of the given \a number using the specified \a base.
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* \todo Make constexpr/template in v5.
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*/
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int digitsum(int number, int base)
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{
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int res = 0;
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while (number > 0) {
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res += number % base;
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number /= base;
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}
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return res;
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}
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/*!
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* \brief Returns the factorial of the given \a number.
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* \todo Make constexpr/template in v5.
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*/
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int factorial(int number)
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{
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int res = 1;
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for (int i = 1; i <= number; ++i) {
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res *= i;
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}
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return res;
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}
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/*!
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* \brief Computes \a base power \a exponent modulo \a module.
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* \todo Make constexpr/template in v5.
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*/
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std::uint64_t powerModulo(const std::uint64_t base, const std::uint64_t exponent, const std::uint64_t module)
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{
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std::uint64_t res = 1;
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for (std::uint64_t mask = 0x8000000000000000; mask; mask >>= 1) {
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if (mask & exponent) {
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res *= base;
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}
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if (mask != 1) {
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res *= res;
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}
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res %= module;
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}
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return res;
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}
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/*!
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* \brief Computes the inverse of \a number modulo \a module.
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* \todo Make constexpr/template in v5.
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*/
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std::int64_t inverseModulo(std::int64_t number, std::int64_t module)
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{
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std::int64_t y1 = 0, y2 = 1, tmp;
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while (number != 1) {
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tmp = y1 - (module / number) * y2;
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y1 = y2;
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y2 = tmp;
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tmp = module % number;
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module = number;
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number = tmp;
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}
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return y2;
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}
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/*!
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* \brief Computes the order of \a number modulo \a module.
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* \todo Make constexpr/template in v5.
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*/
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std::uint64_t orderModulo(const std::uint64_t number, const std::uint64_t module)
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{
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std::uint64_t order = 1;
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for (; powerModulo(number, order, module) != 1 && order != module; ++order)
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;
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return order != module ? order : 0;
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}
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} // namespace MathUtilities
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