poj3641

简单题

快速幂

View Code

#include <iostream>
#include <cstdio>
#include <cstdlib>
#include <cstring>
using namespace std;

long long a, p;

long long power(long long a, long long n)
{
    long long ret = 1;
    for (long long m = a; n > 0; n >>= 1, m = m * m % p)
        if (n & 1)
            ret = ret * m % p;
    return ret;
}

bool prime(int a)
{
    for (int i = 2; i * i <= a; i++)
        if (a % i == 0)
            return false;
    return true;
}

int main()
{
    //freopen("t.txt", "r", stdin);
    while (scanf("%lld%lld", &p, &a), a | p)
    {
        long long x = power(a, p);
        if (x == a && !prime(p))
            printf("yes\n");
        else
            printf("no\n");
    }
    return 0;
}