Leetcode: Climbing stairs

There is a given number of stairs n. Stairs can be either taken two steps at a time or one step at a time. For a height of 1, there is only one possible solution: 1. For a height of 2, there are two solutions: 1-1 or 2. The main trick in this task is to discover that this is a fibonacci-like sequence. Every next step depends on the steps before. Once this is discovered, the code is straightforward. First, cover the base cases, 1 and 2. For the rest, append the sum of the first digits to a list and then pop the first element off the beginning. Finally, return the last digit.

class Solution:
  def climbStairs(self, n: int) -> int:
    if n <= 2:
      return n
    l = [1, 2]
    n -= 2
    while n > 0:
      l.append(l[0]+l[1])
      l=l[1:]
      n -= 1
    return l[1]