003.统计素数个数

package com.pta.two;

public class SuShu
{
    public static void main(String[] args)
    {
        System.out.println(bf(100));
    }

    //暴力算法统计素数
    public static int bf(int n)
    {
        int count = 0;
        for (int i = 2; i < n; i++)
        {
            count += isPrime(i) ? 1 : 0;
        }
        return count;
    }

    private static boolean isPrime(int x)
    {
        for (int i = 2; i *i< x; i++)//i只要小于根号x就可以
        {
            if (x % i == 0)
            {
                return false;
            }
        }
        return true;
    }


}