## Problem Statement

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

**Example 2:**

Input: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

**Solution:**

#iterative approach
class Solution:
def climbStairs(self, n: int) -> int:
if n==0 or n==1:
return n
nums = [0 for i in range(n+1)]
nums[0]=1
nums[1]=1
for i in range(2, n+1):
nums[i] = nums[i-1]+nums[i-2]
return nums[n]