For a binary tree T, we can define a flip operation as follows: choose any node, and swap the left and right child subtrees. A binary tree X is flip equivalent to a binary tree Y if and only if we can make X equal to Y after some number of flip opera…

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 递归 日期 题目地址:https://leetcode.com/problems/flip-equivalent-binary-trees/description/ 题目描述 For a binary tree T, we can define a flip operation as follows: choose any node, and swa…

题目如下: For a binary tree T, we can define a flip operation as follows: choose any node, and swap the left and right child subtrees. A binary tree X is flip equivalent to a binary tree Y if and only if we can make X equal to Y after some number of flip…

https://leetcode.com/problems/flip-equivalent-binary-trees/ For a binary tree T, we can define a flip operation as follows: choose any node, and swap the left and right child subtrees. A binary tree X is flip equivalent to a binary tree Y if and only…

For a binary tree T, we can define a flip operation as follows: choose any node, and swap the left and right child subtrees. A binary tree X is flip equivalent to a binary tree Y if and only if we can make X equal to Y after some number of flip opera…

In a deck of cards, every card has a unique integer.  You can order the deck in any order you want. Initially, all the cards start face down (unrevealed) in one deck. Now, you do the following steps repeatedly, until all cards are revealed: Take the…

Given an array of 4 digits, return the largest 24 hour time that can be made. The smallest 24 hour time is 00:00, and the largest is 23:59.  Starting from 00:00, a time is larger if more time has elapsed since midnight. Return the answer as a string…

我们可以为二叉树 T 定义一个翻转操作,如下所示:选择任意节点,然后交换它的左子树和右子树. 只要经过一定次数的翻转操作后,能使 X 等于 Y,我们就称二叉树 X 翻转等价于二叉树 Y. 编写一个判断两个二叉树是否是翻转等价的函数.这些树由根节点 root1 和 root2 给出. 示例: 输入:root1 = [1,2,3,4,5,6,null,null,null,7,8], root2 = [1,3,2,null,6,4,5,null,null,null,null,8,7] 输出:true…

https://leetcode.com/problems/flip-equivalent-binary-trees/ 判断两棵二叉树是否等价:若两棵二叉树可以通过任意次的交换任意节点的左右子树变为相同,则称两棵二叉树等价. 思路:遍历二叉树,判断所有的子树是否等价. struct TreeNode { int val; TreeNode *left; TreeNode *right; TreeNode(int x) : val(x), left(NULL), right(NULL) {} };…

leetcode weekly contest 43 leetcode649. Dota2 Senate leetcode649.Dota2 Senate 思路: 模拟规则round by round. class Solution { public: string predictPartyVictory(string senate) { int len = senate.size(); int r = 0; int d = 0; int i = 0; while(1) { if(senate[…

LeetCode Weekly Contest 23 1. Reverse String II Given a string and an integer k, you need to reverse the first k characters for every 2k characters counting from the start of the string. If there are less than k characters left, reverse all of them.…

LeetCode Weekly Contest 8 415. Add Strings User Accepted: 765 User Tried: 822 Total Accepted: 789 Total Submissions: 1844 Difficulty: Easy Given two non-negative numbers num1 and num2 represented as string, return the sum of num1 and num2. Note: The…

Weekly Contest 86 A:840. 矩阵中的幻方 3 x 3 的幻方是一个填充有从 1 到 9 的不同数字的 3 x 3 矩阵,其中每行,每列以及两条对角线上的各数之和都相等. 给定一个由整数组成的 N × N 矩阵,其中有多少个 3 × 3 的 “幻方” 子矩阵?(每个子矩阵都是连续的). 直接模拟即可,本来是签到题,由于粗心,浪费了时间. class Solution { public: int numMagicSquaresInside(vector<vector<int&…

A full binary tree is a binary tree where each node has exactly 0 or 2 children. Return a list of all possible full binary trees with Nnodes.  Each element of the answer is the root node of one possible tree. Each node of each tree in the answer must…

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 递归 日期 题目地址:https://leetcode.com/problems/merge-two-binary-trees/description/ 题目描述 Given two binary trees and imagine that when you put one of them to cover the other, some node…

链接:https://leetcode.com/contest/leetcode-weekly-contest-33/ A.Longest Harmonious Subsequence 思路:hash加查找 class Solution { public: int findLHS(vector<int>& nums) { if (nums.empty()) ; ; int len = nums.size(); unordered_map<int, int> hash(len…

有段时间没有写代码了,脑子都生锈了,今后争取笔耕不辍(立flag,以后打脸) 随机一道Leecode题, Merge Two Binary Trees,题目基本描述如下: Given two binary trees and imagine that when you put one of them to cover the other, some nodes of the two trees are overlapped while the others are not. You need t…

[题目链接]:https://leetcode.com/contest/leetcode-weekly-contest-26/problems/split-array-with-equal-sum/ [题意] 让你把一段序列去掉3个元素,然后分成4个部分; 要求这4个部分的和相同; 问你可不可能; [题解] 先枚举要删除的3个元素中的中间那个元素j; 然后把整个序列分成左边和右边两个部分; 然后再左边的序列中枚举i; 然后把0..j-1分成0..i-1和i+1..j-1两个部分; 然后看这两个部…

[题目链接]:https://leetcode.com/contest/leetcode-weekly-contest-26/problems/friend-circles/ [题意] 告诉你任意两个人是不是朋友. 问你最后有多少个连通块; [题解] 裸并查集. [完整代码] #include <bits/stdc++.h> using namespace std; #define lson l,m,rt<<1 #define rson m+1,r,rt<<1|1 #d…

[题目链接]:https://leetcode.com/contest/leetcode-weekly-contest-26/problems/longest-uncommon-subsequence-ii/ [题意] 字符串变成多个了; (不止两个) 让你求最长不公共子序列 [题解] 因为最大长度为10; 所以把每个长度有哪些字符串记录下来; 然后从字符串长度由大到小枚举len; 假设这个答案序列为len长度的某个字符串; 然后看看len长度的字符串有没有和它一样的字符串(即出现两次及以上)…

[题目链接]:https://leetcode.com/contest/leetcode-weekly-contest-26/problems/longest-uncommon-subsequence-i/ [题意] 让你求两个字符串的最长不公共子序列的长度; 即这个序列是两个字符串中的一个的子序列; 同时要求这个序列不是所有其他任意一个字符串的子序列; [题解] 两个字符串相同就无解; 否则输出两个字符串的长度中较大者; [完整代码] #include <bits/stdc++.h> usi…

原题 Given two binary trees and imagine that when you put one of them to cover the other, some nodes of the two trees are overlapped while the others are not. You need to merge them into a new binary tree. The merge rule is that if two nodes overlap, t…

Given a binary tree, determine if it is a complete binary tree. Definition of a complete binary tree from Wikipedia:In a complete binary tree every level, except possibly the last, is completely filled, and all nodes in the last level are as far left…

In an array A of 0s and 1s, how many non-empty subarrays have sum S? Example 1: Input: A = [1,0,1,0,1], S = 2 Output: 4 Explanation: The 4 subarrays are bolded below: [1,0,1,0,1] [1,0,1,0,1] [1,0,1,0,1] [1,0,1,0,1] Note: A.length <= 30000 0 <= S <…

这是悦乐书的第274次更新,第290篇原创 01 看题和准备 今天介绍的是LeetCode算法题中Easy级别的第142题(顺位题号是617).提供两个二叉树,将其合并为新的二叉树,也可以在其中一个二叉树上进行覆盖.合并规则是如果两个节点重叠(都不为空),则将节点值加起来作为合并节点的新值. 否则,其中一个不为空的节点将用作新树的节点.例如: Tree 1 Tree 2 1 2 / \ / \ 3 2 1 3 / \ \ 5 4 7 合并后的新二叉树: 3 / \ 4 5 / \ \ 5 4 7…

已经正式在实习了,好久都没有刷题了(应该有半年了吧),感觉还是不能把思维锻炼落下,所以决定每周末刷一次LeetCode. 这是第一周(菜的真实,只做了两题,还有半小时不想看了,冷~). 第一题: 965. Univalued Binary Tree 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 univalu…

1, 543. Diameter of Binary Tree 维护左右子树的高度,同时更新结果,返回以该节点结束的最大长度.递归调用. /** * Definition for a binary tree node. * struct TreeNode { * int val; * TreeNode *left; * TreeNode *right; * TreeNode(int x) : val(x), left(NULL), right(NULL) {} * }; */ class Sol…

leetcode现在每周末举办比赛,这是今天上午参加的比赛的题解.题目难度不算大,两个easy,一个medium,一个hard.hard题之前接触过,所以做得比较顺利. 1.  Sum of Left Leaves(Leetcode 404 Easy) Find the sum of all left leaves in a given binary tree. Example: 3 / \ 9 20 / \ 15 7 There are two left leaves in the binar…

闲着无聊参加了这个比赛,我刚加入战场的时候时间已经过了三分多钟,这个时候已经有20多个大佬做出了4分题,我一脸懵逼地打开第一道题 665. Non-decreasing Array My SubmissionsBack to Contest   User Accepted:1054 User Tried:1755 Total Accepted:1080 Total Submissions:7519 Difficulty:Easy Given an array with n integers, y…

要死要死,第一题竟然错误8次,心态崩了呀,自己没有考虑清楚,STL用的也不是很熟,一直犯错. 第二题也是在室友的帮助下完成的,心态崩了. 970. Powerful Integers Given two non-negative integers x and y, an integer is powerful if it is equal to x^i + y^j for some integers i >= 0 and j >= 0. Return a list of all powerfu…