return its level order traversal as: [ [3], [9,20], [15,7] ] Solution: #Definition for a binary tree node.#class TreeNode(object):#def __init__(self, x):#self.val = x#self.left = None#self.right = NoneclassSolution(object):deflevelOrder(self, root):""":type root: TreeNo...
classSolution:v_min=-sys.maxsize-1v_max=sys.maxsize+1defisValidBST(self,root:TreeNode)->bool:ifnotroot:returnFalsereturnself._checkSubTree(root,self.v_min,self.v_max)def_checkSubTree(self,node:TreeNode,v_min:int,v_max:int)->bool:ifnotnode:returnTrueifnode.val<=v_minornode.val>=v...
链接:https://leetcode-cn.com/problems/binary-tree-inorder-traversal python # 0094.二叉树中序遍历 # 递归 & 迭代 class Solution: def inOrderRecur(self,head: TreeNode) -> int: """ 递归遍历,LNR, 左根右 :param head: :return: """ def traversal(head): # 递归终止条件 ifhead== None: ...
[Leetcode][python]Binary Tree Zigzag Level Order Traversal,题目大意按之字形遍历二叉树(一正一反)解题思路来自:链接解题思路:这道题和上一题层序遍历那道题差不多,区别只是在于奇数层的节点要翻转过来存入数组。代码:代码BFSclassSolution(object):defzigzagLeve
[Leetcode][python]Binary Tree Preorder Traversal/二叉树的前序遍历,题目大意二叉树前序遍历挑战:迭代解题解题思路递归简单
Python 代码 fromcollectionsimportdeque# 定义二叉树节点classTreeNode:def__init__(self,val=0,left=None,right=None):self.val=valself.left=leftself.right=rightdeflevelOrder(root):# 如果根节点为空,返回空列表ifnotroot:return[]# 初始化队列和结果列表queue=deque([root])result=[]whilequeue:level_siz...
In a postorder traversal of the vertices of T, we visit the vertices of T1 in postorder, then the vertices of T2 in postorder and finally we visit r. Now you are given the preorder sequence and inorder sequence of a certain binary tree. Try to find out its postorder sequence. ...
Python: 代码语言:javascript 代码运行次数:0 运行 AI代码解释 classSolution:definorderTraversal(self,root:TreeNode)->List[int]:#初始化数组、栈 res,stack=list(),list()#当前节点指向根节点 cur=root #递归条件为:栈或当前节点非空whilestack or cur:ifcur:#当前节点非空时入栈 ...
Python Code:# Definition: Binary tree node. class TreeNode(object): def __init__(self, x): self.val = x self.left = None self.right = None def delete_Node(root, key): # if root doesn't exist, just return it if not root: return root # Find the node in the left...
6. Kth Smallest in BSTWrite a Python program to find the kth smallest element in a given binary search tree.Sample Solution: Python Code:class TreeNode(object): def __init__(self, x): self.val = x self.left = None self.right = None def kth_smallest(root, k): stac...