Hackerrank Day 9: Recursion 3 | Hackerrank Solutions in Ruby

Objective
Today, we're learning and practicing an algorithmic concept called Recursion. Check out the Tutorial tab for learning materials and an instructional video!

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.

Here is the Solution

	N = gets.to_i
	def factorial(num)
	if num == 0 || num == 1
	return 1
	end
	return num * factorial(num-1)
	end
	print factorial N