1.题目基本信息

1.1.题目描述

给定一棵二叉树的根节点 root ，请找出该二叉树中每一层的最大值。

1.2.题目地址

https://leetcode.cn/problems/find-largest-value-in-each-tree-row/description/

2.解题方法

2.1.解题思路

层序遍历

3.解题代码

python3代码

# 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
from collections import deque
class Solution:
    def largestValues(self, root: Optional[TreeNode]) -> List[int]:
        # 思路：层序遍历
        if root is None:
            return []
        que = deque([root])
        result = []
        while que:
            size = len(que)
            maxVal = -inf
            for i in range(size):
                node = que.popleft()
                maxVal = max(maxVal, node.val)
                if node.left:
                    que.append(node.left)
                if node.right:
                    que.append(node.right)
            result.append(maxVal)
        return result

4.执行结果