Namaste Coders 👩‍💻

Before starting have a glance on the below article to know about functions in Python 👇

Built-in Functions User Defined Functions Lambda Functions

What is Recursion 🤔?

Recursion is simply self calling of a function. It is a technique of writing a function. In recursion we divide complex problem into simpler problem and than we find a solution for simpler problem which leads to solving the complex problem.

In recursion We have to think of following to solve a problem 👇

• Base case: It will end the recursion and will provide the required answer
• Simpler solution: It will lead towards complex problem solution.

Stacks are used behind the scene in recursion.

Example: We are going to learn how to find the factorial of a number. Suppose we need to find factorial of 5. 5!=54321

Recursively: Let’s make a function fact(num) which will take num as a parameter.

Simpler Solution: fact(num)=num*fact(num-1)

Base Case: if num=1 return 1

# Factorial of a number recursively

def fact(num):
    if(num==1):
        return 1
    ans=num*fact(num-1)
    return ans

num=5
ans=fact(num)
print("Factorial is :",num)

#Output:
#Factorial is : 5

Here is the tree structure of recursion. First, we go forward till the base case is hit. Then, it moves backward resulting into the output

Here is the stack which is created in the memory 👇

For more reference do watch the video tutorial

Factorial

Fibonnaci Numbers

P.S. : Will continue with the functions and discuss more in upcoming articles. Stay tuned👧

The End

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