'''
Description: 
Autor: Au3C2
Date: 2021-01-20 16:16:37
LastEditors: Au3C2
LastEditTime: 2021-01-20 16:16:59
'''
# Definition for a binary tree node.
# class TreeNode:
#     def __init__(self, val=0, left=None, right=None):
#         self.val = val
#         self.left = left
#         self.right = right
class Solution:
    def searchBST(self, root: TreeNode, val: int) -> TreeNode:
        if not root:
            return
        if root.val == val:
            return root
        if root.val > val:
            return self.searchBST(root.left,val)
        if root.val < val:
            return self.searchBST(root.right,val)
# 树，简单。就是二分查找
# https://leetcode-cn.com/problems/search-in-a-binary-search-tree/