HDU 2669 Romantic（扩展欧几里德）

题目链接：http://acm.hdu.edu.cn/showproblem.php?pid=2669

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.

77 51
10 44
34 79

2 -3
sorry
7 -3

PS:

扩展欧几里德模板题。

附：扩展欧几里德解说：http://blog.csdn.net/u012860063/article/details/39760003

代码例如以下：

#include <cstdio>
#include <cstring>
#include <cmath>
typedef __int64 LL;

LL exgcd(LL a,LL b,LL &x,LL &y)
{
    if(b == 0)
    {
        x = 1;
        y = 0;
        return a;
    }
    LL r = exgcd(b,a%b,x,y);
    LL t = x;
    x = y;
    y = t-a/b*y;
    return r;
}

int main()
{
    LL a,b,x,y;
    while(scanf("%I64d%I64d",&a,&b)!=EOF)
    {
        LL d = exgcd(a,b,x,y);
        if(1%d)//不能整除
            printf("sorry\n");
        else
        {
            while(x<0)
                x+=b,y-=a;
            printf("%I64d %I64d\n",x,y);
        }
    }
    return 0;
}