Intro to Recursion

We all heard about DSA and its need. In DSA we come across a topic known as "Recursion" and Today I will give a brief intro of it to you. So recursion in basic words is "calling itself". So in a function when we call the same function in itself, This condition is called Recursion.

Let's take an example:

In this, I have taken a code for factorial. Let's see the code below:

int factorial(int n){

    if(n == 0 ){
        return 1;
    }
    int smalloutput = factorial(n-1);
    int output = n * smalloutput;
    return output;
}

So analyzing this code :

1. Firstly, a function will be declared, here it is named factorial in which we pass int n as an argument.

2. So let's deep dive into this, and remember the topic we study in mathematics known as the Principle of Mathematical induction. In the concept, we take a base case and then an inductive case. So in this code, as the base code I have defined if n is equal to zero then return 1 as 0!=1. After this, we assume that at n-1 the statement holds true (2nd statement of PMI). We will take a variable output in which we will store the value of n*smallOutput where smallOutput is the factorial of n-1 terms. And Lastly, we will return the value of the output.

Let's now print the code :

#include<iostream>
using namespace std;

int factorial(int n){

    if(n == 0 ){
        return 1;
    }
    int smalloutput = factorial(n-1);
    int output = n * smalloutput;
    return output;

}

int main(){
    int n;
    cin>> n;

    cout << factorial(n) << endl;

}

The output of the code will be:

Reading it for the first time can be overwhelming but it will come as easy when we move forward. So chill learn it steadily and easily. Be consistent and if u like it make sure to follow me and also drop suggestions.

Thanks,

Yash