HDU 2669 【Exgcd正宗模板】

 Romantic

Time Limit:1000MS Memory Limit:32768KB 64bit IO Format:%I64d & %I64u

 

Description
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.
Input
The input contains multiple test cases.
Each case two nonnegative integer a,b (0<a, b<=2^31)
Output
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.
Sample Input
77 51
10 44
34 79
Sample Output
2 -3
sorry

7 -3

题意：求ax+by=1的最小x非负解;

思路：Exgcd即可；

失误：用int 就是wa，估计一下用int可以的，这种东西以后不要费心啦直接LL吧；

AC代码：

#include<cstdio>typedef long long LL;LL Exgcd(LL a,LL b,LL &x,LL &y){if(!b){x=1; y=0;return a;}LL R=Exgcd(b,a%b,y,x);y-=a/b*x;return R; }  int main(){LL a,b;while(~scanf("%lld %lld",&a,&b)){LL x=0,y=0; LL d=Exgcd(a,b,x,y);if(1%d) {printf("sorry\n");continue;}x=1/d*x;LL mod=b/d;x=(x%mod+mod)%mod;y=(1-a*x)/b;printf("%lld %lld\n",x,y);}return 0;}