JavaAlgorithms/Maths/KrishnamurthyNumber.java

package Maths;

/* This is a program to check if a number is a Krishnamurthy number or not.
A number is a Krishnamurthy number if the sum of the factorials of the digits of the number is equal to the number itself.
For example, 1, 2 and 145 are Krishnamurthy numbers.
Krishnamurthy number is also referred to as a Strong number.
*/

import java.io.*;

public class KrishnamurthyNumber
{
	//returns True if the number is a Krishnamurthy number and False if it is not.
	public static boolean isKMurthy(int n)
	{
		//initialising the variable s that will store the sum of the factorials of the digits to 0
		int s=0;
		//storing the number n in a temporary variable tmp
		int tmp=n;

		//Krishnamurthy numbers are positive
		if(n<=0)
		{
			return false;
		}

		//checking if the number is a Krishnamurthy number
		else
		{
			while(n!=0)
			{
				//initialising the variable fact that will store the factorials of the digits
				int fact=1;
				//computing factorial of each digit
				for (int i=1;i<=n%10;i++)
				{
					fact=fact*i;
				}
				//computing the sum of the factorials
				s=s+fact;
				//discarding the digit for which factorial has been calculated
				n=n/10;
			}

			//evaluating if sum of the factorials of the digits equals the number itself
			if(tmp==s)
			{
				return true;
			}
			else
			{
				return false;
			}
		}
	}
	public static void main(String args[]) throws IOException
	{
		BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
		System.out.println("Enter a number to check if it is a Krishnamurthy number: ");
		int n=Integer.parseInt(br.readLine());
		if(isKMurthy(n))
		{
			System.out.println(n+" is a Krishnamurthy number.");
		}
		else
		{
			System.out.println(n+" is NOT a Krishnamurthy number.");
		}
	}
}