HDU 2.1.2 How many prime numbers_how many prime numbers 杭电-优快云博客

本文介绍了一个简单的C语言程序，用于判断输入的整数是否为素数，并统计给定集合中素数的数量。该程序使用了sqrt函数来优化素数判断过程。

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How many prime numbers

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

Total Submission(s): 8122 Accepted Submission(s): 2619

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

OJ上用pow(x,0.5)会导致complier error

sqrt需要把参数转换为double，不然也会出错

菜鸟级的原创代码，已AC。若有可提高之处欢迎指导

#include<stdio.h>  
#include<math.h>  
bool isPrime(int x)  
{  
    if (x == 2)return true;  
    int i = sqrt((double)x)+1;  
    while (--i>1)  
    if (x%i == 0)return false;  
    return true;  
}  
int main()  
{  
    int n,total,temp;  
    while (scanf("%d", &n) == 1)  
    {  
        total = 0;  
        while (n--)  
        {  
            scanf("%d", &temp);  
            if (isPrime(temp))  
                total++;  
        }  
        printf("%d\n", total);   
    }  
    return 0;  
}