10 Simple Recursion Programs in Python

What is Recursion? Recursion is a technique where a function calls itself to solve a smaller version of the same problem. Every recursive function must have: Base Case → Stops the recursion Recursive Case → Calls the function again with a smaller input 1. Factorial of a Number The factorial of a number n is the product of all positive integers up to n. def factorial ( n ): if n == 0 or n == 1 : return 1 return n * factorial ( n - 1 ) print ( factorial ( 5 )) 2. Sum of First N Numbers This program calculates the sum of numbers from 1 to n. def sum_n ( n ): if n == 0 : return 0 return n + sum_n ( n - 1 ) print ( sum_n ( 5 )) 3. Print Numbers from 1 to N Print numbers in ascending order using recursion. def print_1_to_n ( n ): if n == 0 : return print_1_to_n ( n - 1 ) print ( n ) print_1_to_n ( 5 ) 4. Print Numbers from N to 1 Print numbers in descending order. def print_n_to_1 ( n ): if n == 0 : return print ( n ) print_n_to_1 ( n - 1 ) print_n_to_1 ( 5 ) 5. Fibonacci Series (Nth Term) E