Created
October 20, 2013 05:04
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Wikioi 1200 - 同余方程
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/* Wikioi - Problem 1200 Equation. by Abreto. */ | |
#include <stdio.h> | |
#define ABS(x) ( ((x)>0) ? (x) : (-(x)) ) | |
int exgcd(int m, int n, int * x) | |
{ | |
int q = 0; | |
int x0 = 1, x1 = 0; | |
int t = 0; | |
while(n != 0) | |
{ | |
q = m / n; | |
t = m; m = n; n = t % n; | |
t = x0; x0 = x1; x1 = t - q*x1; | |
} | |
*x = x0; | |
return m; | |
} | |
int main(void) | |
{ | |
int a = 0, b = 0; | |
int g = 0, x = 0; | |
int t = 0; | |
scanf("%d %d", &a, &b); | |
g = exgcd(a, -b, &x); | |
x *= g; | |
t = ABS(b/g); | |
while( x < 0 ) x += t; | |
while( x > t ) x -= t; | |
printf("%d\n", x); | |
return 0; | |
} |
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