CountPrimes.java

package com.learning.leet.math;

/**
 * Created by sargonbenjamin on 7/15/19.
 * https://leetcode.com/explore/interview/card/top-interview-questions-easy/102/math/744/
 */
public class CountPrimes {

    public int countPrimes(int n) {
        if(n<=1)return 0;
        int count = 0;
        for(int i = 2; i<n; i++){
            if(isPrime(i))count++;
        }

        return count;
    }

    public boolean isPrime(int val){

        for(int i = 2 ; i<=Math.sqrt(val); i++) {
            if(val%i == 0)return false;
        }

        return true;
    }

}