[Python手撕]爬楼梯（组合总数，不需去重）

class Solution:
    def climbStairs(self, n: int) -> int:
        if n == 1 or n == 2:
            return n

        dp = [0] * (n + 1)
        dp[1] = 1
        dp[2] = 2

        for i in range(3, n + 1):
            dp[i] = dp[i - 1] + dp[i - 2]

        return dp[-1]