A happy number is a number which eventually reaches 1 when replaced by the sum of the square of each digit. For example, consider the number 320.

3² + 2² + 0² ⇒ 9 + 4 + 0 = 13
1² + 3² ⇒ 1 + 9 = 10
1² + 0² ⇒ 1 + 0 = 1

Hence, 320 is a Happy Number.

Write a program in Java to enter a number and check if it is a Happy Number or not.

import java.util.Scanner;

public class KboatHappyNumber
{
    public static void main(String args[]) {
        Scanner in = new Scanner(System.in);
        System.out.print("Enter number to check: ");
        long num = in.nextLong();
        long sum = 0;
        long n = num;
        do {
            sum = 0;
            while (n != 0) {
                int d = (int)(n % 10);
                sum += d * d;
                n /= 10;
            }
            n = sum;
        } while (sum > 6);

        if (sum == 1) {
            System.out.println(num + " is a Happy Number");
        }
        else {
            System.out.println(num + " is not a Happy Number");
        }
    }
}