HDU 2138 How many prime numbers

 1 #include <bits/stdc++.h>
 2 using namespace std;
 3 typedef long long LL;
 4 LL quickPow(LL a,LL d,LL n){
 5     LL ret = 1;
 6     while(d){
 7         if(d&1) ret = (ret*a)%n;
 8         d >>= 1;
 9         a = (a*a)%n;
10     }
11     return ret;
12 }
13 bool check(int a,int d,int n){
14     if(n == a) return true;
15     while(~d&1) d >>= 1;
16     LL t = quickPow(a,d,n);
17     while(d < n-1 && t != 1 && t != n-1){
18         t = t*t%n;
19         d <<= 1;
20     }
21     return (d&1) || t == n-1;
22 }
23 bool isP(int n){
24     if(n == 2) return true;
25     if(n < 2 || 0 == (n&1)) return false;
26     static int p[3] = {2,3,61};
27     for(int i = 0; i < 3; ++i)
28         if(!check(p[i],n-1,n)) return false;
29     return true;
30 }
31 int main(){
32     int n,cnt,tmp;
33     while(~scanf("%d",&n)){
34         cnt = 0;
35         while(n--){
36             scanf("%d",&tmp);
37             cnt += isP(tmp);
38         }
39         printf("%d\n",cnt);
40     }
41     return 0;
42 }