QPP/problems/fibonacisequence/description.md

Fibonacci Number

Write a function called fibonacci that takes a non-negative integer n as input and returns the n-th Fibonacci number.

The Fibonacci sequence is defined as:

• F(0) = 0
• F(1) = 1
• F(n) = F(n-1) + F(n-2) for n > 1

Function Signature:

def fibonacci(n):
    # return your solution

Requirements

• The function should return the n-th number in the Fibonacci sequence.

• If n is less than 0, print "Incorrect input".

• Your function will be tested with:

  • Base cases (n = 0 and n = 1)
  • Small values of n
  • Larger values of n (e.g., 9)
  • Multiple test cases in sequence

Example:

fibonacci(0)   # returns 0
fibonacci(1)   # returns 1
fibonacci(2)   # returns 1
fibonacci(3)   # returns 2
fibonacci(5)   # returns 5
fibonacci(9)   # returns 34

You can copy this into your problem’s solution description.