Leetcode 700. Search in a Binary Search Tree

# Definition for a binary tree node.
# class TreeNode:
#     def __init__(self, x):
#         self.val = x
#         self.left = None
#         self.right = None
import functools

class Solution:
    @functools.lru_cache()
    def searchBST(self, root: TreeNode, val: int) -> TreeNode:
        if not root:
            return 
        if root.val==val:
            return root
        elif root.val<val:
            return self.searchBST(root.right,val)
        else:
            return self.searchBST(root.left,val)