HackerRank-Solutions/Java/Advanced/Prime Checker/Solution.java

//     Author: Rodney Shaghoulian
//     Github: github.com/RodneyShag
// HackerRank: hackerrank.com/RodneyShag

import java.io.*;
import java.util.*;
import java.text.*;
import java.math.*;
import java.util.regex.*;
import java.lang.reflect.*;

import static java.lang.System.in;

class Prime {
    void checkPrime(int... numbers) {
        for (int num : numbers) {
            if (isPrime(num)) {
                System.out.print(num + " ");
            }
        }
        System.out.println();
    }
    
    boolean isPrime(int n) {
        if (n < 2) {
            return false;
        } else if (n == 2) {     // account for even numbers now, so that we can do i+=2 in loop below
            return true;
        } else if (n % 2 == 0) { // account for even numbers now, so that we can do i+=2 in loop below
            return false;
        }
        int sqrt = (int) Math.sqrt(n);
        for (int i = 3; i <= sqrt; i += 2) { // skips even numbers for faster results
            if (n % i == 0) {
                return false;
            }
        }
        return true;
    }
}

public class Solution {
    public static void main(String[] args) {
        try {
            BufferedReader br = new BufferedReader(new InputStreamReader(in));
            int n1 = Integer.parseInt(br.readLine());
            int n2 = Integer.parseInt(br.readLine());
            int n3 = Integer.parseInt(br.readLine());
            int n4 = Integer.parseInt(br.readLine());
            int n5 = Integer.parseInt(br.readLine());
            Prime ob = new Prime();
            ob.checkPrime(n1);
            ob.checkPrime(n1,n2);
            ob.checkPrime(n1,n2,n3);
            ob.checkPrime(n1,n2,n3,n4,n5);
            Method[] methods = Prime.class.getDeclaredMethods();
            Set<String> set = new HashSet<>();
            boolean overload = false;
            for (int i = 0; i < methods.length; i++) {
                if (set.contains(methods[i].getName())) {
                    overload = true;
                    break;
                }
                set.add(methods[i].getName());
            }
            if (overload) {
                throw new Exception("Overloading not allowed");
            }
        } catch (Exception e) {
            System.out.println(e);
        }
    }
}