70. Climbing Stairs - LeetCode Solution

class Solution:
    
    def climbStairs(self, n: int) -> int:
        
        
        def climb(n, x):
            if n<0:
                return 0
            if n==0:
                return 1
            
            if x[n] != -1:
                return x[n]
            
            else:
                x[n] = climb(n-1, x) + climb(n-2, x)
                return x[n]


            
        return climb(n, [-1] *(n+1))