Java Interface HackerRank Solution with Explanation

For solve this problem you first you need to understand about Interface in Java.

What is Interface in Java?

A Java interface can only contain method signatures and fields. The interface can be used to achieve polymorphism.

• Interface in Java with examples  

Problem Description :

You are given an interface AdvancedArithmetic which contains a method signature int divisor_sum(int n). You need to write a class called MyCalculator which implements the interface.

divisor_sum function just takes an integer as input and return the sum of all its divisors. For example divisors of 6 are 1, 2, 3 and 6, so divisor_sum should return 12. The value of n will be at most 1000.

Read the partially completed code in the editor and complete it. You just need to write the MyCalculator class only.

See full problem description :

• https://www.hackerrank.com/challenges/java-interface/problem 

Lets see solution now.

Solution explanation :

In code editor, we already have AdvancedArithmetic Interface and divisor_sum abstract method. We just have to create new class called MyCalculator, implements AdvancedArithmetic interface and its provide implementation to divisor_sum method.

import java.util.*;
interface AdvancedArithmetic {
  int divisor_sum(int n);
}

//Write your code here
class MyCalculator implements AdvancedArithmetic {
   public int divisor_sum(int n) {
        int ans = 0;
        for (int i=1; i<= n; i++) {
            if (n % i == 0) {
                ans = ans + i;
            }
        }
        return ans;
    }
}

class Solution{
    public static void main(String []args){
        MyCalculator my_calculator = new MyCalculator();
        System.out.print("I implemented: ");
        ImplementedInterfaceNames(my_calculator);
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        System.out.print(my_calculator.divisor_sum(n) + "\n");
          sc.close();
    }
    /*
     *  ImplementedInterfaceNames method takes an object and 
     *  prints the name of the interfaces it implemented
     */
    static void ImplementedInterfaceNames(Object o){
        Class[] theInterfaces = o.getClass().getInterfaces();
        for (int i = 0; i < theInterfaces.length; i++){
            String interfaceName = theInterfaces[i].getName();
            System.out.println(interfaceName);
        }
    }
}

Code Explanation :

• Declare on int variable and initialize with 0. 
• Traverse loop through 1 to n (provided from method parameter).
• We have to return sum of all divisor of n value. So in if condition we are checking that n value is dividable by current ith value or not (means we are getting 0 as modulo or not.).
• If current value is divisor, increment ans + current ith value.
• Return ans.

 

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