Recursion is a technique in programming where a function calls itself repeatedly until a certain condition is met. Recursion is an important concept in many programming languages, including Python.
In this article, we will discuss recursion in Python and provide examples of how it can be used.
How Recursion Works
Recursion works by breaking down a problem into smaller subproblems until a base case is reached. The base case is a condition that, once met, stops the recursion and returns a value.
Each recursive call makes progress toward the base case by reducing the problem to a smaller size. Eventually, the problem becomes small enough to solve directly, and the function returns a value that is used to solve the larger problem.
Find Factorial Of a Number
A classic example of recursion is the calculation of a factorial. A factorial is the product of all positive integers up to a given number.
For example, the factorial of 4 is 4 x 3 x 2 x 1 = 24.
The factorial function can be defined recursively as follows:
def factorial(n):
if n == 0:
return 1
else:
return n * factorial(n - 1)
In this function, we check if the input parameter n is equal to 0. If it is, we return 1, as the factorial of 0 is 1. If n is not 0, we return n multiplied by the factorial of n - 1.
Let’s test this function with some sample inputs:
print(factorial(0)) # 1
print(factorial(5)) # 120
print(factorial(10)) # 3628800
Output:
1
120
3628800
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