The Fibonacci sequence is dened as follows: the rst number of the sequence is 0, the second number is 1, and the nth number is the sum of the (n - 1)th and (n - 2)th numbers. Write a function that takes in an integer n and returns the nth Fibonacci number.
Sample input: 6
Sample output: 5 (0, 1, 1, 2, 3, 5)
We can use a Stack here
Check this Python code.