HDU 2138 How many prime numbers

How many prime numbers

Time Limit: 3000/1000 MS (Java/Others)    Memory Limit: 32768/32768 K (Java/Others)
Total Submission(s): 16170    Accepted Submission(s): 5578

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

32 3 4

 

Sample Output

2

 

Author

wangye

 

Source

HDU 2007-11 Programming Contest_WarmUp

 

这道题=.=

很好很水很神奇。

他说在32位以内，数太大了打表肯定不行。然后这题可以直接判定素数暴力过……

#include<stdio.h>#include<string.h>#include<math.h>int main(){int n;int i,j,a;while(~scanf("%d",&n)){int ans=0,flag=0;for(i=0;i<n;i++){scanf("%d",&a);for(j=2;j<=sqrt(1.0*a);j++){if(a%j==0){flag=1;break;}}if(!flag)ans++;flag=0;}printf("%d\n",ans);}return 0;}