Math
Dynamic Programming
Memoization
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?
Example 1
Input: n = 2
Output: 2
Explanation: 1. 1 step + 1 step
2. 2 steps
Example 2
Input: n = 3
Output: 3
Explanation: 1. 1+1+1
2. 1+2
3. 2+1