题解 | 二叉树的最大深度

# 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 root TreeNode类 
# @return int整型
#
class Solution:
    def maxDepth(self , root: TreeNode) -> int:
        # write code here
        if not root:
            return 0
        left_depth = self.maxDepth(root.left)
        right_depth = self.maxDepth(root.right)
    
        return max(left_depth, right_depth) + 1