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?
Note: Given n will be a positive integer.
Example 1:
Input: 2
Output: 2
Explanation: There are two ways to climb to the top.
1. 1 step + 1 step
2. 2 steps
Example 2:
Input: 3
Output: 3
Explanation: There are three ways to climb to the top.
1. 1 step + 1 step + 1 step
2. 1 step + 2 steps
3. 2 steps + 1 step
class Solution:
     def climbStairs(self, n):
         """
         :type n: int
         :rtype: int
         """
         a = 1
         b = 2
         if n < 2:
             return 1
         for i in range(n-2):
             a,b = b, a+b
             
         return b
class Solution:
     def climbStairs(self, n):
         """
         :type n: int
         :rtype: int
         """
         a = 1
         b = 2
         if n < 2:
             return 1
         for i in range(n-2):
             a,b = b, a+b
             
         return b