LeetCode:. 70 stairs

Suppose you are climbing stairs. N order you need to get to the roof.

Every time you can climb one or two steps. How many different ways can climb to the roof of it?

Note: Given n is a positive integer.

Example 1:

Input: 2
Output: 2
explanation: There are two methods can climb the roof.
1.1 + 1-order-order
2.2 Order
Example 2:

Input: 3
Output: 3
Explanation: There are three methods can climb to the roof.
1.1 + 1 order + 1-order-order
2.1 + 2-order order
3.2 + 1-order-order

class Solution:
    def climbStairs(self, n: int) -> int:
        prev,current = 0,1
        # n = 1 :  1
        # n = 2 :  2
        # n = 3 :  3 = 2 + 1
        # n = 4 :  5 = 3 + 2
        #........
        for i in range(n):
            prev,current = current,prev+current
        return current

Source: stay button (LeetCode)
link: https: //leetcode-cn.com/problems/climbing-stairs
copyrighted by deduction from all networks. Commercial reprint please contact the authorized official, non-commercial reprint please indicate the source.