# class TreeNode:
#     def __init__(self, x):
#         self.val = x
#         self.left = None
#         self.right = None
#
# 代码中的类名、方法名、参数名已经指定,请勿修改,直接返回方法规定的值即可
#
# 
# @param pRoot TreeNode类 
# @return int整型
#
class Solution:
    def TreeDepth(self , pRoot: TreeNode) -> int:
        # write code here
        # 先判空节点
        if not pRoot:
            return 0
        return max(self.TreeDepth(pRoot.left),self.TreeDepth(pRoot.right)) + 1
  1. 树经常和递归结合,要注意递归结束条件,和递归的入口