How many prime numbers（素数）

Problem Description

  Give you a lot of positive integers, just to find out how many prime numbers there are.

 

Input

  There are a lot of cases. In each case, there is an integer N representing the number of integers to find. Each integer won’t exceed 32-bit signed integer, and each of them won’t be less than 2.

 

Output

  For each case, print the number of prime numbers you have found out.

 

Sample Input

3
2 3 4

 

Sample Output

2

 

Author

wangye

 

Source

HDU 2007-11 Programming Contest_WarmUp

 #include<stdio.h>
 #include<math.h>
   int prime(int x)
     {  int i;
         if(x<=)   return ;
         for(i=;i<=sqrt(x*1.0);i++)   //i*i<=x  是会超时的，因为i*i每次都要计算
           {
               if(x%i==)
                 {
                     return ;
                     break;
                 }
           }
         return ;
     }
   int main()
     {
         int n;
         int i;
         int sum;
         int a;
         while(scanf("%d",&n)!=EOF)
           {
                  sum=;
                for(i=;i<n;i++)
                 {
                     scanf("%d",&a);
                       if(prime(a))
                         sum++;
                 }
               printf("%d\n",sum);
           }
         return ;

     }