Python Recursion

In Python, a function can call itself. This technique is called recursion. It allows a function to solve a problem by breaking it down into smaller versions of the same problem.

Think of recursion like looking into a mirror that reflects another mirror—each layer keeps repeating the same pattern until a stopping point.

When to use recursion?

Recursion is useful for problems like:

Calculating factorials
Finding Fibonacci numbers
Traversing nested structures (like folders or trees)

Example: Calculating Factorial Recursively

Let’s write a custom factorial function using recursion:

				
					def compute_factorial(n):
    if n <= 1:
        return 1
    return n * compute_factorial(n - 1)

number = 6
print("Number:", number)
print("Factorial:", compute_factorial(number))

Output:

				
					Number: 6
Factorial: 720

How it works:

The function keeps calling itself with a smaller number.
When it reaches n <= 1, it returns 1.
Then all the previous calls multiply the numbers step-by-step until the original number’s factorial is formed.

Summary

Recursion lets you solve problems by having a function call itself. However, it must always include a base case (a stopping condition) or it could run infinitely.