DudeneyNumber.java

/**
 * A number is said to be Dudeney if the sum of the digits, is the cube root of the entered number.
 * Example- Let the number be 512, its sum of digits is 5+1+2=8. The cube root of 512 is also 8.
 *          Since, the sum of the digits is equal to the cube root of the entered number;
 *          it is a Dudeney Number.
 */
package com.thealgorithms.maths;

import java.io.*;

public class DudeneyNumber {

    //returns True if the number is a Dudeney number and False if it is not a Dudeney number.
    public static boolean isDudeney(int n) {
        // Calculating Cube Root
        int cube_root = (int) (Math.round((Math.pow(n, 1.0 / 3.0))));
        // If the number is not a perfect cube the method returns false.
        if (cube_root * cube_root * cube_root != n) {
            return false;
        }
        int sum_of_digits = 0;// Stores the sums of the digit of the entered number
        int temp = n;//A temporary variable to store the entered number
        // Loop to calculate sum of the digits.
        while (temp > 0) {

            // Extracting Last digit of the number
            int rem = temp % 10;

            // Calculating sum of digits.
            sum_of_digits += rem;

            // Removing the last digit
            temp /= 10;
        }

        //If the cube root of the number is not equal to the sum of its digits we return false.  
        if (cube_root != sum_of_digits) {
            return false;
        }

        return true;
    }

    /**
     * Method to check if number is Dudeney Number or Not 1) Input - Enter a
     * Number: 512 Output - It is a Dudeney Number. 2) Input - Enter a Number:
     * 125 Output - It is not a Dudeney Number.
     */
    public static void main(String args[]) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        System.out.println("Enter a Number: ");
        int n = Integer.parseInt(br.readLine());
        if (isDudeney(n)) {
            System.out.println("It is a Dudeney Number.");
        } else {
            System.out.println("It is not a Dudeney Number.");
        }
    }
}