Hacker Rank 30 days of code Day 9: Recursion

The problem:

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.

My submission

 #include <cmath>  
 #include <cstdio>  
 #include <vector>  
 #include <iostream>  
 #include <algorithm>  
 using namespace std;  
 int factorial(int n){  
   if(n==1)return 1;  
   else return n*factorial(n-1);  
 }  
 int main() {  
   /* Enter your code here. Read input from STDIN. Print output to STDOUT */   
   int n;  
   cin>>n;  
   cout<<factorial(n)<<endl;  
   return 0;  
 }