HDU 2.1.2 How Many prime numbers

分析：不用打表发，直接判断是不是素数。注意Math.sqrt(x).

import java.util.Arrays;import java.util.Scanner;public class Main {public static boolean isPrime(int x){//x !=1if(x==2) return true;for(int i=2;i<Math.sqrt(x)+1;i++){if(x%i==0) return false;}return true;}public static void main(String[] args) {Scanner in=new Scanner(System.in);while(in.hasNext()){int n = in.nextInt();int sum=0;while(0 != n--){if(isPrime(in.nextInt())){sum++;}}System.out.println(sum);}}}