Day 9: Recursion - HackerRank 30 days of code solution

Objective
Today, we're learning and practicing an algorithmic concept called Recursion.

Recursive Method for Calculating Factorial 

Task
Write a factorial function that takes a positive integer,  as a parameter and prints the result of  ( factorial).

Note: If you fail to use recursion or fail to name your recursive function factorial or Factorial, you will get a score of .

Input Format

A single integer,  (the argument to pass to factorial).

Constraints

• Your submission must contain a recursive function named factorial.

Output Format

Print a single integer denoting .

Sample Input

3

Sample Output

6

Explanation

Consider the following steps:

From steps  and , we can say ; then when we apply the value from  to step , we get . Thus, we print  as our answer.

Solution :

import java.io.*;

import java.util.*;

import java.text.*;

import java.math.*;

import java.util.regex.*;

public class Solution {

    public static void main(String[] args) {

        /* Enter your code here. Read input from STDIN. Print output to STDOUT. Your class should be named Solution. */

        Scanner in = new Scanner(System.in);

        

            while(in.hasNext())

            {

           long n = in.nextLong();

        long factofnum =factorial(n);

        System.out.println(factofnum);

        }    

    }

    

    public static long factorial(long n)

        {

        if(n==0 || n==1)

            {

            return 1;

        }

        else

            return n*factorial(n-1);

    }

}