HDU 2669 Romantic

扩展GCD

#include<cstdio>
#include<cstring>
#include<cmath>
#include<iostream>
#include<algorithm>
using namespace std;

__int64 extgcd(__int64 a, __int64 b, __int64 & x, __int64 & y)
{
    if (b == 0) { x=1; y=0; return a; }
    __int64 d = extgcd(b, a % b, x, y);
    __int64 t = x; x = y; y = t - a / b * y;
    return d;
}

int main()
{
    __int64 a,b,ansx,ansy;
    while(cin>>a>>b)
    {
        extgcd(a,b,ansx,ansy);
        if(a*ansx==1-b*ansy)
        {
            while(ansx<0)
            {
                ansx=ansx+b;
                ansy=ansy-a;
            }
            cout<<ansx<<" "<<ansy<<endl;
        }
        else cout<<"sorry"<<endl;
    }
    return 0;
}