题解 | 二叉树的最大深度

极速省流版：

# 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:
        if not root:
            return 0
        return 1+max(self.maxDepth(root.right),self.maxDepth(root.left))
            
        # write code here

非迭代版：可防止迭代溢出

import queue
# 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:
        if not root:
            return 0
        maxdepth=0
        q=queue.Queue()
        q.put(root)
        while not q.empty():
            maxdepth += 1
            for _ in range(q.qsize()):
                temp=q.get()
                if temp.left:
                    q.put(temp.left)
                if temp.right:
                    q.put(temp.right)
        return maxdepth

        # write code here