poj1061青蛙的约会（扩展欧几里得）

Description

Input

Output

Sample Input

1 2 3 4 5

Sample Output

4

Source

#include<cstdio>
#include<iostream>
#include<algorithm>
#include<cstring>
using namespace std;
__int64 x,y,m,n,l,d,a,b,c,temp;


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


int main()
{
    __int64 x1,k,ans;
    while(~scanf("%I64d%I64d%I64d%I64d%I64d",&x,&y,&m,&n,&l))
    {
        a=n-m;
        b=l;
        c=x-y;
        d=gcd(a,b);
        if(c%d!=0)
        {
            printf("Impossible\n");
            continue;
        }
        x=x*(c/d);//x为原不定方程的一组解。。
        k=-x*d/b;
        ans=x+k*b/d;
        if(ans<0)
            ans=ans+b/d;
        printf("%I64d\n",ans);
    }
    return 0;
}