How many prime numbers

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

Total Submission(s): 8205 Accepted Submission(s): 2642

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

Author wangye

Source HDU 2007-11 Programming Contest_WarmUp

解题思路：直接判定是否为素数即可。

AC代码：

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               using namespace std; #define INF 0x7fffffff bool isprim(int n){ //判断是否为素数 for(int i=2; i<=(double)sqrt((double)n); i++){ if(n%i == 0) return false; } return true; } int main() { #ifdef sxk freopen("in.txt","r",stdin); #endif int n, x, ans; while(scanf("%d",&n)!=EOF) { ans = 0; //计数 while(n--){ scanf("%d", &x); if(isprim(x)) ans ++; } printf("%d\n", ans); } return 0; }

hdu 2138 How many prime numbers (素数判定）

How many prime numbers