90 lines
1.8 KiB
C++
90 lines
1.8 KiB
C++
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/*
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** Command & Conquer Red Alert(tm)
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** Copyright 2025 Electronic Arts Inc.
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**
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** This program is free software: you can redistribute it and/or modify
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** it under the terms of the GNU General Public License as published by
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** the Free Software Foundation, either version 3 of the License, or
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** (at your option) any later version.
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**
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** This program is distributed in the hope that it will be useful,
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** but WITHOUT ANY WARRANTY; without even the implied warranty of
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** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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** GNU General Public License for more details.
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**
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** You should have received a copy of the GNU General Public License
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** along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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/*
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** Method to raise a number by an arbitrary whole exponent and then
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** modulo the result by another number.
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*/
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unsigned long Power_Mod(unsigned long root, unsigned long exponent, unsigned long mod)
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{
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unsigned long s = 1;
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unsigned long t = root;
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unsigned long u = exponent;
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while (u) {
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if (u & 1) {
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s = (s*t) % mod;
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}
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u >>= 1;
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t = (t*t) % mod;
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}
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return(s);
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}
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/*
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** This routine finds the greatest common divisor common
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** to two specified numbers.
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*/
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int Greatest_Common_Divisor(int x, int y)
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{
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if (x < 0) {
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x = -x;
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}
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if (y < 0) {
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y = -y;
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}
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if (x + y == 0) {
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return(0); // This is an error condition.
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}
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int greatest = y;
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while (x > 0) {
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greatest = x;
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x = y % x;
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y = greatest;
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}
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return(g);
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}
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/*
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** Computes the greatest common divisor for a vector
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** of integers.
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*/
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int Grestest_Common_Divisor(int count, int * data)
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{
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if (count < 1) {
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return(0);
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}
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greatest = data[0];
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for (int i = 1; i < count; i++) {
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greatest = Greatest_Common_Divisor(greatest, data[i]);
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if (greatest == 1) {
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return(1);
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}
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}
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return(greatest);
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}
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