拓展欧几里得算法

#include<cstdio>
#include<iostream>
#include<cstdlib>
#include<iomanip>
#include<cmath>
#include<cstring>
#include<string>
#include<algorithm>
using namespace std;
long long x,y,m,n,L;
void exgcd(long long a,long long b,long long &d,long long &x,long long &y)
{
    long long t;
    if(b==0)
    {
        d=a;x=1;y=0;
    }
    else
    {
        exgcd(b,a%b,d,x,y);
        t=x;x=y;y=t-(a/b)*y;
    }
}
int main()
{
    long long a,b,d,x,y;
    cin>>a>>b;
    exgcd(a,b,d,x,y);
    cout<<(x/d%(b/d)+b/d)%(b/d)<<endl;
    return 0;
}