python LeetCode exam record 70

topic

Suppose you are climbing stairs. It takes n steps for you to reach the top of the building.

You can climb 1 or 2 steps at a time. How many different ways can you climb to the top of a building?

code

# 核心思想：将到达n层的次数转化为到达n-1层和n-2层的次数和
# 原因：因为一次只能走1步或者2步，所以到达该层只有两种方案，即n-1和n-2，然后计算这两层的方案数
class Solution:
    def climbStairs(self, n: int) -> int:
        ls = [i for i in range(1, n+1)]
        for i in range(2, n):
            ls[i] = ls[i-1]+ls[i-2]
        return ls[n-1]