70. Climbing Stairs Leetcode Python solution

Climbing_stairs.py

This problem has typically 3-4 approaches .I'm gonna show two of them here .
1. DYANAMIC PROGRAMMING APPROACH .
```python3 
class Solution:
    def climbStairs(self, n: int) -> int:
        if n==0:
            return 0
        if n==1:
            return 1 
        dp=[0]*(n+1)
        dp[1]=1
        dp[2]=2
        for i in range (3,n+1):
            dp[i]=dp[i-1]+dp[i-2]
        return dp[n]   
 ```

2. RECURSION WITH MEMOISATION 
```python3 
class Solution:
    def climbStairs(self, n: int) -> int:
        memo=[0]*(n+1)
        
        def recursion(i,n ,memo):
            if i>n:
                return 0
            if i==n:
                return 1
            if memo[i]>0:
                return memo[i]
            memo[i]=recursion(i+1,n,memo)+recursion(i+2,n,memo)
            return memo[i]
        return recursion(0,n,memo)
```