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Java Interface HackerRank Solution with Explanation

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.

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 :

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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