Count Primes

1不是prime，明白了吗！！！！

知道如何求prime

public class Solution {    public int countPrimes(int n) {        boolean[] prime = new boolean[n];        Arrays.fill(prime, true);        for (int i = 2; i < n; i++) {            if (prime[i]) {                for (int j = i*2; j < n; j = i + j) {                    prime[j] = false;                }            }        }        int count = 0;        for (int i = 2; i < n; i++) {            if (prime[i]) {                count++;            }        }        //return count + 1;        return count;    }}