题目
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?
解题思路
dp, dp[i]=dp[i-1]+dp[i-2]，因为到第n级台阶，可以由n-1或者n-2级台阶走到
代码
class Solution:
def climbStairs(self, n: int) -> int:
dp1, dp2 = 1, 2
for i in range(n - 1):
dp1, dp2 = dp2, dp1 + dp2
return dp1
