poj 3641 Pseudoprime numbers

原题链接：http://poj.org/problem?id=3641
快速幂。。

#include<algorithm>#include<iostream>#include<cstdlib>#include<cstring>#include<cstdio>#include<vector>#include<set>using std::min;using std::sort;using std::pair;using std::swap;using std::vector;using std::multiset;#define pb(e) push_back(e)#define sz(c) (int)(c).size()#define mp(a, b) make_pair(a, b)#define all(c) (c).begin(), (c).end()#define iter(c) __typeof((c).begin())#define cls(arr, val) memset(arr, val, sizeof(arr))#define cpresent(c, e) (find(all(c), (e)) != (c).end())#define rep(i, n) for(int i = 0; i < (int)n; i++)#define tr(c, i) for(iter(c) i = (c).begin(); i != (c).end(); ++i)const int N = 1 << 17;const int INF = ~0u >> 1;typedef unsigned long long ull;bool isPrime(ull n) {    for(int i = 2; (ull)i * i <= n; i++ ) {        if(n % i == 0) {            return false;        }    }    return n != 1;}ull mod_pow(ull a, ull p) {    ull ans = 1, M = p;    while(p) {        if(p & 1) ans = ans * a % M;        a = a * a % M;        p >>= 1;    }    return ans;}int main() {#ifdef LOCAL    freopen("in.txt", "r", stdin);    freopen("out.txt", "w+", stdout);#endif    ull a, p;    while(~scanf("%lld %lld", &p, &a), a + p) {        if(isPrime(p)) { puts("no"); continue; }        puts(a % p == mod_pow(a, p) ? "yes" : "no");    }    return 0;}