450. Delete Node in a BST
450. Delete Node in a BST
這個題目給定的條件可以很簡單：給定一個數值，要我們在二元搜尋樹中找到哪個節點的數值等於此值，並且刪掉他。
LeetCode
752. Open the Lock
752. Open the Lock
class Solution:
def openLock(self, deadends:
104. Maximum Depth of Binary Tree
104. Maximum Depth of Binary Tree
# Definition for a binary
652. Find Duplicate Subtrees
652. Find Duplicate Subtrees
建議先做過 536. Construct Binary Tree from
113. Path Sum II
113. Path Sum II
這一題比較困難的是，雖然是樹的遍歷加上回溯法。
# Definition for a binary
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，
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
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，
255. Verify Preorder Sequence in Binary Search Tree
255. Verify Preorder Sequence in Binary Search Tree
遞迴（超時）