[Leetcode] 70. Climbing Stairs

문제 바로가기

Time Complexity: O(n)
Space Complexity: O(1)

class Solution:
    def climbStairs(self, n: int) -> int:
        prev, pprev = 2, 1
        if n == 1:
            return 1
        if n == 2:
            return 2
        
        res = 0
        for i in range(2, n):
            res = prev + pprev
            pprev, prev = prev, res
        
        return res