数论-线性方程——Program H

The Sky is Sprite. 
The Birds is Fly in the Sky. 
The Wind is Wonderful. 
Blew Throw the Trees 
Trees are Shaking, Leaves are Falling. 
Lovers Walk passing, and so are You. 
................................Write in English class by yifenfei 



Girls are clever and bright. In HDU every girl like math. Every girl like to solve math problem! 
Now tell you two nonnegative integer a and b. Find the nonnegative integer X and integer Y to satisfy X*a + Y*b = 1. If no such answer print "sorry" instead. 

The input contains multiple test cases. 
Each case two nonnegative integer a,b (0<a, b<=2^31) 

output nonnegative integer X and integer Y, if there are more answers than the X smaller one will be choosed. If no answer put "sorry" instead. 

#include <iostream>
#include <cstdio>


using namespace std;
void gcd(long long a,long long b,long long &d,long long &x,long long &y)
{
	if(!b)
	{
		d=a;
		x=1;
		y=0;
	}
	else
	{
		gcd(b,a%b,d,y,x);
		y-=x*(a/b);
	}
}
int main()
{
	long long  a,b;
	while(scanf("%lld%lld",&a,&b)==2)
	{
		long long d,x,y;
		gcd(a,b,d,x,y);
		if(d==1)
		{
			while(x<0)
			{
				x=x+b;
				y=y-a;
			}
			printf("%lld %lld\n",x,y);
		}
		else
			printf("sorry\n");
	}
	return 0;
}