114. Flatten Binary Tree to Linked List
114. Flatten Binary Tree to Linked List
這一是後續遍歷很經典的一道題目，體現了後續遍歷很重要的一個精神，當後續遍歷到一半，
LeetCode
652. Find Duplicate Subtrees
652. Find Duplicate Subtrees
建議先做過 536. Construct Binary Tree from
543. Diameter of Binary Tree
543. Diameter of Binary Tree
這一題和 124. Binary Tree Maximum
429. N-ary Tree Level Order Traversal
429. N-ary Tree Level Order Traversal
可以先做這題 116. Populating Next
417. Pacific Atlantic Water Flow
417. Pacific Atlantic Water Flow
廣度優先搜索
BFS 也可以利用一次把多個點加入 queue 後再開始出發，
752. Open the Lock
752. Open the Lock
class Solution:
def openLock(self, deadends:
111. Minimum Depth of Binary Tree
111. Minimum Depth of Binary Tree
# Definition for a binary
104. Maximum Depth of Binary Tree
104. Maximum Depth of Binary Tree
# Definition for a binary
572. Subtree of Another Tree
# Definition for a binary tree node.
# class TreeNode:
# def __init_
428. Serialize and Deserialize N-ary Tree
428. Serialize and Deserialize N-ary Tree