题解 | #二叉树的深度#

# 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
        if not pRoot:
            return 0
        if pRoot.left is None and pRoot.right is None:
            return 1

        return max(self.TreeDepth(pRoot.left),self.TreeDepth(pRoot.right))+1

以上方法用递归，空间O(N)，但题目要求O(1)。

递归思路：找最深左子树或最深右子树的高度

ref:

https://blog.nowcoder.net/n/17332a8453f442f8b4cade938903de5d