hdu 2138

How many prime numbers

Time Limit: 3000/1000 MS (Java/Others) Memory Limit: 32768/32768 K (Java/Others)

Total Submission(s): 7352 Accepted Submission(s): 2360

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

 

Recommend

威士忌

#include<iostream>
#include<math.h>
using namespace std;

int isprime(int x)
{
    int i;
    
    for(i=2;i<=sqrt(x);i++)           //用sqrt避免超时
        if(x%i==0)
            return 0;
    return 1;
}
int main()
{
    int n,i,cnt;
    int a[1000];
    while(cin>>n&&n)
    {
        cnt=0;
        for(i=0;i<n;i++)
            cin>>a[i];
        for(i=0;i<n;i++)
            if(isprime(a[i]))
                cnt++;
        cout<<cnt<<endl;
    }
    return 0;
}