You are climbing a stair case. It takes n steps to reach to the top.
Each time you can either climb 1 or 2 steps. In how many distinct ways can you climb to the top?
Input: 2
Output: 2
Explanation: There are two ways to climb to the top.
1. 1 step + 1 step
2. 2 steps
# The answer is the same as the example
# It's also Fibonacci
# This post explains it well
# https://leetcode.com/problems/climbing-stairs/discuss/25299/Basically-it's-a-fibonacci.
class Solution:
def climbStairs(self, n: int) -> int:
if not n:
return None
if n == 1:
return 1
if n == 2:
return 2
d = [float("inf") for i in range(n)]
d[0] = 1
d[1] = 2
for i in range(2, n):
d[i] = d[i - 1] + d[i - 2]
return d[-1]