Fibonacci Number

Problem

Return the n-th Fibonacci number with F(0) = 0 and F(1) = 1, computed iteratively in O(n) time and O(1) space.

The sequence satisfies F(n) = F(n-1) + F(n-2) for n >= 2. Assume n is a non-negative integer.

Hint

Keep only the last two values and roll them forward n times.

case 1

in: [0]

expected: 0

case 2

in: [1]

expected: 1

case 3

in: [10]

expected: 55

case 4

in: [30]

expected: 832040

case 5

in: [45]

expected: 1134903170

Starter codePython

def fibonacci(n):
    # Your code here
    pass

5 test cases · run your code against them in the editor