Nice work! We’ll demonstrate another classic recursive function: fibonacci().

fibonacci() should return the Nth Fibonacci number, where N is the number given as input. The first two numbers of a Fibonacci Sequence start with 0 and 1. Every subsequent number is the sum of the previous two.

Our recursive implementation:

# runtime: Exponential - O(2^N) def fibonacci(n): if n < 0: ValueError("Input 0 or greater only!") if n <= 1: return n return fibonacci(n - 1) + fibonacci(n - 2) fibonacci(3) # 2 fibonacci(7) # 13 fibonacci(0) # 0



Implement your version of fibonacci() which has the same functionality without using any recursive calls!

Folder Icon

Sign up to start coding

By signing up for Codecademy, you agree to Codecademy's Terms of Service & Privacy Policy.

Already have an account?