一、学习视频

【二叉树的层序遍历【基础算法精讲 13】】 https://www.bilibili.com/video/BV1hG4y1277i/?share_source=copy_web&vd_source=dc0e55cfae3b304619670a78444fd795

二、跟练代码

1.102. 二叉树的层序遍历

# 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
class Solution:def levelOrder(self, root: Optional[TreeNode]) -> List[List[int]]:# 双列表if not root:return []# 现在节点、子节点、现在节点值列表cur, ans = [root], []while cur:nxt, val = [], []# 遍历现在节点列表for x in cur:val.append(x.val)if x.left:nxt.append(x.left)if x.right:nxt.append(x.right)ans.append(val)cur = nxtreturn ans

（未完待续）