Day_19_Solution.java

/**
 * Title   : Day_19_Solution.java
 * Author  : Tridib Samanta
 * Created : 13-01-2020
 * Link    : https://www.hackerrank.com/challenges/30-interfaces/problem
 **/

import java.io.*;
import java.util.*;

interface AdvancedArithmetic{
   int divisorSum(int n);
}
class Calculator implements AdvancedArithmetic {
    public int divisorSum(int n) {
        int sum = 0;
        int sqrt = (int) Math.sqrt(n);
        int stepSize = (n % 2 == 1) ? 2 : 1;
        for (int i = 1; i <= sqrt; i += stepSize) {
            if (n % i == 0) {
                sum += i + n/i;
            }
        }
        if (sqrt * sqrt == n) {
            sum -= sqrt;
        }
        return sum;
    }
}
class Day_19_Solution {

    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);
        int n = scan.nextInt();
        scan.close();

      	AdvancedArithmetic myCalculator = new Calculator();
        int sum = myCalculator.divisorSum(n);
        System.out.println("I implemented: " + myCalculator.getClass().getInterfaces()[0].getName() );
        System.out.println(sum);
    }
}