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297. Serialize and Deserialize Binary Tree # bfs(큐) 또는 dfs(preorder 순회: 나-좌-우) # null 대신 N 으로 DFS: preorder 가 더 쉽게 구현 가능 https://youtu.be/u4JAi2JJhI8 # Definition for a binary tree node.# class TreeNode(object):# def __init__(self, x):# self.val = x# self.left = None# self.right = Noneclass Codec: def serialize(self, root): """Encodes a tree to a single stri..

235. Lowest Common Ancestor of a Binary Search Tree https://youtu.be/gs2LMfuOR9k?si=KNjrz6AwcGwSPR0P # Definition for a binary tree node.# class TreeNode:# def __init__(self, x):# self.val = x# self.left = None# self.right = Noneclass Solution: def lowestCommonAncestor(self, root: 'TreeNode', p: 'TreeNode', q: 'TreeNode') -> 'TreeNode': # 공통 부모 찾기 # p..

572. Subtree of Another Tree # 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 = rightclass Solution: def isSubtree(self, root: Optional[TreeNode], subRoot: Optional[TreeNode]) -> bool: def sameTree(n1, n2): if not n1 and not n2: # 둘다 없으면 ..

110. Balanced Binary Tree # 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 = rightclass Solution: def isBalanced(self, root: Optional[TreeNode]) -> bool: # 높이 균형 이진 트리는 각 노드의 두 서브 트리의 깊이가 1 이상 차이가 나지 않는 이진 트리입니다. # height-balanced tree: 높이 균형 이진 트리는, ..

543. Diameter of Binary Tree 트리의 Diameter 즉, 지름을 구하려면,어떤 노드를 기준으로, 좌측 최장 길이+오른쪽 최장 길이..꼭. 이 노드가 root 가 아닐 수도 있음: The path does not necessarily have to pass through the root.위 의 경우, 노드 3을 기준으로, 왼쪽 2, 오른쪽 2... 그래서 diameter 는 2+2=4 임 따라서,전역 변수 max_length 만들고, 모든 노드를 탐색하면서, 왼쪽+오른쪽 길이, 즉, max_lengh를 계속 업데이트 해야함. 모든 노드 탐색시, dfs,,,로 # Definition for a binary tree node.# class TreeNode:# def __init_..

Design Binary Search TreeSolved MediumDesign a Binary Search Tree class.You will design a Tree Map, which maps an integer key to an integer value. Your Tree class should support the following operations:TreeMap() will initialize an binary search tree map.void insert(int key, int val) will map the key to the value and insert it into the tree.int get(int key) will return the value mapped with the ..

https://youtu.be/U4hFQCa1Cq0?si=qOfcXWT90Uo5RjvE  """# Definition for a Node.class Node: def __init__(self, val: int = 0, left: 'Node' = None, right: 'Node' = None, next: 'Node' = None): self.val = val self.left = left self.right = right self.next = next"""class Solution: def connect(self, root: 'Optional[Node]') -> 'Optional[Node]': cur, nxt = root, root..

Binary Tree Right Side ViewSolved MediumYou are given the root of a binary tree. Return only the values of the nodes that are visible from the right side of the tree, ordered from top to bottom.Example 1:Input: root = [1,2,3]Output: [1,3]CopyExample 2:Input: root = [1,2,3,4,5,6,7]Output: [1,3,7]CopyConstraints:0 -100 # Definition for a binary tree node.# class TreeNode:# def __init__(self, v..

102. Binary Tree Level Order Traversal # 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 = rightclass Solution: def levelOrder(self, root: Optional[TreeNode]) -> List[List[int]]: if not root: # root 없으면 return [] res = [] q = deque([r..