Fibonacci Number

Problem Statement:

The Fibonacci numbers, commonly denoted F(n) form a sequence, called the Fibonacci sequence, such that each number is the sum of the two preceding ones, starting from 0 and 1. That is,
F(0) = 0,   F(1) = 1
F(N) = F(N - 1) + F(N - 2), for N > 1.
Given N, calculate F(N).

Example 1:
Input: 2
Output: 1
Explanation: F(2) = F(1) + F(0) = 1 + 0 = 1.

Example 2:
Input: 3
Output: 2
Explanation: F(3) = F(2) + F(1) = 1 + 1 = 2.

Example 3:
Input: 4
Output: 3
Explanation: F(4) = F(3) + F(2) = 2 + 1 = 3.
 
 
 
Solution:

class Solution(object):
    def fib(self, N):
        """
        :type N: int
        :rtype: int
        """
        li=[0,1]
        if N<2:
            return(li[N])
        for i in range(2,N+1):
            li.append(li[i-1]+li[i-2])
        return(li[-1])