Climbing Stairs in Kotlin

You are climbing a staircase. It takes n steps to reach the top.

Each time you can climb either 1 or 2 steps. In how many distinct ways can you climb to the top? Two ways are different when their moves come in a different order: climbing 1 step and then 2 is not the same as climbing 2 and then 1.

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

Example 3:

Input: n = 4
Output: 5
Explanation: There are five ways to climb to the top:
1. 1 step + 1 step + 1 step + 1 step
2. 1 step + 1 step + 2 steps
3. 1 step + 2 steps + 1 step
4. 2 steps + 1 step + 1 step
5. 2 steps + 2 steps

Constraints:

• 1 <= n <= 45
• The answer always fits in a 32-bit integer.