hyunkookim 님의 블로그

129. Sum Root to Leaf Numbers # 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 sumNumbers(self, root: Optional[TreeNode]) -> int: stack = [] def dfs(node, curString): if not node: return ..

112. Path Sum # 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 hasPathSum(self, root: Optional[TreeNode], targetSum: int) -> bool: # DFS로.. def dfs(node, curSum): if not node: return False ..

114. Flatten Binary Tree to Linked List # 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 flatten(self, root: Optional[TreeNode]) -> None: """ Do not return anything, modify root in-place instead. """ # preorder..

117. Populating Next Right Pointers in Each Node II https://youtu.be/68RmOoq-OSs?si=-Ss1BuJuc5nIqS5A """# 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"""# 큐로 품class Solution: def connect(self, root: 'Node') ->..

106. Construct Binary Tree from Inorder and Postorder 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 buildTree(self, inorder: List[int], postorder: List[int]) -> Optional[TreeNode]: # inorder: 왼, 중, 오 # postoder:..

101. Symmetric Tree https://youtu.be/Mao9uzxwvmc?si=yG0AiWstMVMAGJxt # 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 isSymmetric(self, root: Optional[TreeNode]) -> bool: def dfs(left, right): if not left and not right: ..

226. Invert Binary Tree https://youtu.be/OnSn2XEQ4MY?si=M8XrLJXb_NV2PHRw 정말 쉽고, 기본적인 문제라는데, .. 그리고, DFS 로.. , DFS 이면,, 재귀로.. # 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 invertTree(self, root: Optional[TreeNode]) -> Optional[TreeNode]..

146. LRU Cache https://youtu.be/7ABFKPK2hD4?si=R9ZwBAdBVxHzBRga # Node 추가 class Node: def __init__(self, key, val): self.key, self.val = key, val self.prev = self.next = Noneclass LRUCache: def __init__(self, capacity: int): self.capacity = capacity self.cache = {} # map key to node # left=LRU, right=most recent self.left, self.right = Node(0, 0), ..

86. Partition List class Solution: def partition(self, head: Optional[ListNode], x: int) -> Optional[ListNode]: """ x 기준값보다, 작은 더미 노드 리스트, 큰 더미 노드 리스트를 만들어서 이어주기 """ # 작은 값 리스트와 큰 값 리스트의 더미 노드 생성 small_dummy = ListNode(0) large_dummy = ListNode(0) # 포인터 초기화 small = small_dummy # 작은 값 리스트의 끝 large = large_dummy # ..

61. Rotate List # Definition for singly-linked list.# class ListNode:# def __init__(self, val=0, next=None):# self.val = val# self.next = nextclass Solution: def rotateRight(self, head: Optional[ListNode], k: int) -> Optional[ListNode]: if not head or not head.next or k == 0: # 예외 처리: 리스트가 비었거나 노드가 하나인 경우 return head # 1. 리스트 길이 계산 length =..