## Question

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

**Example 2:**

Input:n = 3Output:3Explanation: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

**Constraints:**

`1 <= n <= 45`

## Python Solution

class Solution: def climbStairs(self, n: int) -> int: a=b=1 for _ in range(n): a,b=b,a+b return a