1.题目描述 2.问题分析 遍历一遍树,然后将所有节点的数值放入到一个set中,最后检查set中元素的个数是否为1. 3.代码 bool isUnivalTree(TreeNode* root) { set<int> s; preOrder(root, s); ; } void preOrder(TreeNode* root, set<int> &s) { if (root == NULL) return; s.insert(root->val); preOrder(…

作者: 负雪明烛 id: fuxuemingzhu 个人博客: http://fuxuemingzhu.cn/ 目录 题目描述 题目大意 解题方法 BFS DFS 日期 题目地址:https://leetcode.com/problems/univalued-binary-tree/ 题目描述 A binary tree is univalued if every node in the tree has the same value. Return true if and only if th…

题目如下: A binary tree is univalued if every node in the tree has the same value. Return true if and only if the given tree is univalued. Example 1: Input: [1,1,1,1,1,null,1] Output: true Example 2: Input: [2,2,2,5,2] Output: false Note: The number of n…

题目: Given inorder and postorder traversal of a tree, construct the binary tree. Note:You may assume that duplicates do not exist in the tree. 说明: 1)实现与根据先序和中序遍历构造二叉树相似,题目参考请进 算法思想 中序序列:C.B.E.D.F.A.H.G.J.I   后序序列:C.E.F.D.B.H.J.I.G.A   递归思路: 根据后序遍历的特点,…

1.题目描述 2.问题分析 DFS. 3.代码 bool isBalanced(TreeNode* root) { if (root == NULL) return true; && isBalanced(root->left) && isBalanced(root->right); } int height(TreeNode *node) { if (node == NULL) ; if (node->left == NULL && no…

总是在看完别人的代码之后,才发现自己的差距! 我的递归: 先把左侧扁平化,再把右侧扁平化. 然后找到左侧最后一个节点,把右侧移动过去. 然后把左侧整体移到右侧,左侧置为空. 很复杂吧! 如果节点很长的话,这个耗时是很大的.O(n^2) ?差不多了! 菜逼啊!时间估计都错了!!! 时间是多少呢? while 最左侧的数,会不断被遍历!是这样的.大概会被遍历o(n)次 所以还是O(n^2)? 反正是复杂了. void flatten(struct TreeNode* root) { if(root…

题目来源: https://leetcode.com/problems/univalued-binary-tree/submissions/ 自我感觉难度/真实难度: 题意: 分析: 自己的代码: class Solution(object): def isUnivalTree(self, root): """ :type root: TreeNode :rtype: bool """ return self.dsf(root.val,root)…

原题链接在这里:https://leetcode.com/problems/construct-string-from-binary-tree/#/description 题目: You need to construct a string consists of parenthesis and integers from a binary tree with the preorder traversing way. The null node needs to be represented b…

题目链接:Balanced Binary Tree | LeetCode OJ Given a binary tree, determine if it is height-balanced. For this problem, a height-balanced binary tree is defined as a binary tree in which the depth of the two subtrees of every node never differ by more tha…

Serialization is the process of converting a data structure or object into a sequence of bits so that it can be stored in a file or memory buffer, or transmitted across a network connection link to be reconstructed later in the same or another comput…