Climbing Stairs (LeetCode #70)

Challenge Statement

• You are climbing a staircase. It takes n steps to reach the top.
• Each time you can either climb 1 or 2 steps. In how many distinct ways can you climb to the top?
• This challenge corresponds to LeetCode #70.

Constraints

• 1 <= n <= 45

Example 1:

Input: n = 2
Output: 2
Explanation: There are two ways to climb to the top.
1. 1 step + 1 step
2. 2 steps

Example 2:

Input: n = 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

Solution

Below is my solution and some test cases. This solution has a linear time complexity O(n) and a linear space complexity O(n), where n is the number of steps.