HDU2138 How many prime numbers

PS: 素数判定问题。

#include <iostream>#include <cstdio>#include <algorithm>using namespace std;long long pow_mod(long long a, long long i, long long n) {    if(i==0) return 1%n;    long long tmp = pow_mod(a, i>>1, n); // int tmp. WA.    tmp = tmp*tmp%n;    if(i&1) tmp = (long long)tmp*a%n;    return tmp;}bool test(int n, int a, int d) {    if(n==2) return true;    if(n==a) return true;    if((n&1)==0) return false;    while(!(d&1)) d = d>>1;    int t = pow_mod(a, d, n);    while((d!=n-1) && (t!=1) && (t!=n-1)) {        t = (long long)t*t%n;        d = d << 1;    }    return (t==n-1 || (d&1)==1);}bool isPrime(int n) {    if(n<2) return false;   // int a[] = {2, 3 , 5, 7, 11, 13, 17};    int a[] = {2, 3, 5};    for(int i = 0; i <= 2; i++) {        if(!test(n, a[i], n-1)) return false;    }    return true;}int main(){    int n, t, cnt;    while(scanf("%d", &n)!=EOF) {        int *p = new int[n+5];        for(int i = 0; i < n; i++) {            scanf("%d", &t);            p[i] = t;        }        cnt = 0;        for(int i = 0; i < n; i++) {            if(isPrime(p[i])) cnt++;        }        printf("%d\n", cnt);    }    return 0;}