Pseudoprime numbers（POJ 3641 快速幂）

#include <cstring>
#include <cstdio>
#include <iostream>
#include <cmath>
#include <algorithm>
using namespace std;
#define LL long long
LL p,res,a;
bool judge_prime(LL k)
{
    LL i;
    LL u=int(sqrt(k*1.0));
    for(i=2;i<=u;i++)
    {
        if(k%i==0)
            return 0;
    }
    return 1;
}
int main()
{
    freopen("in.txt","r",stdin);
    while(scanf("%lld%lld",&p,&a))
    {
        if(p==0&&a==0)
            break;
        if(judge_prime(p))
        {
            printf("no
");
            continue;
        }
        res=1;
        LL t=p;
        LL w=a;
        while(p)
        {
            if(p&1) res=(res*a)%t;
            a=(a*a)%t;
            p>>=1;
        }
        if(res==w)
            printf("yes
");
        else
            printf("no
");
    }
}