14级结训赛3314-扩展欧几里德

#include<stdio.h>
#include<string.h>
#include<stdlib.h>
#define NN 500004
#define NL 1000
using namespace std;
void gcd(int a,int b, int &x, int &y)
{
    if(!b)
    {
        x = 1; y = 0;
    }
    else
    {
        gcd(b,a%b,y,x);
        y -= x*(a/b);
    }
}
int main()
{
    int k , x;
    int n, m;
    while(~scanf("%d%d",&m,&n))
    {
        k = x = 1;
        gcd(m,n,k,x);
        if(k < 0)
        k = k+n;
        printf("%d\n",k);
    }
    return 0;
}