In this problem, a rooted tree is a directed graph such that, there is exactly one node (the root) for which all other nodes are descendants of this node, plus every node has exactly one parent, except for the root node which has no parents. The give…

In this problem, a rooted tree is a directed graph such that, there is exactly one node (the root) for which all other nodes are descendants of this node, plus every node has exactly one parent, except for the root node which has no parents. The give…

原题链接在这里:https://leetcode.com/problems/redundant-connection-ii/ 题目: In this problem, a rooted tree is a directed graph such that, there is exactly one node (the root) for which all other nodes are descendants of this node, plus every node has exactly…

In this problem, a tree is an undirected graph that is connected and has no cycles. The given input is a graph that started as a tree with N nodes (with distinct values 1, 2, ..., N), with one additional edge added. The added edge has two different v…

In this problem, a rooted tree is a directed graph such that, there is exactly one node (the root) for which all other nodes are descendants of this node, plus every node has exactly one parent, except for the root node which has no parents. The give…

lc 684 Redundant Connection 684 Redundant Connection In this problem, a tree is an undirected graph that is connected and has no cycles. The given input is a graph that started as a tree with N nodes (with distinct values 1, 2, ..., N), with one addi…

685. 冗余连接 II 在本问题中,有根树指满足以下条件的有向图.该树只有一个根节点,所有其他节点都是该根节点的后继.每一个节点只有一个父节点,除了根节点没有父节点. 输入一个有向图,该图由一个有着N个节点 (节点值不重复1, 2, -, N) 的树及一条附加的边构成.附加的边的两个顶点包含在1到N中间,这条附加的边不属于树中已存在的边. 结果图是一个以边组成的二维数组. 每一个边 的元素是一对 [u, v],用以表示有向图中连接顶点 u and v和顶点的边,其中父节点u是子节点v的一个父节…

In this problem, a rooted tree is a directed graph such that, there is exactly one node (the root) for which all other nodes are descendants of this node, plus every node has exactly one parent, except for the root node which has no parents. The give…

We are given a "tree" in the form of a 2D-array, with distinct values for each node. In the given 2D-array, each element pair [u, v] represents that v is a child of u in the tree. We can remove exactly one redundant pair in this "tree"…

题目: In this problem, a tree is an undirected graph that is connected and has no cycles. The given input is a graph that started as a tree with N nodes (with distinct values 1, 2, ..., N), with one additional edge added. The added edge has two differe…

In this problem, a tree is an undirected graph that is connected and has no cycles. The given input is a graph that started as a tree with N nodes (with distinct values 1, 2, ..., N), with one additional edge added. The added edge has two different v…

A 2d grid map of m rows and n columns is initially filled with water. We may perform an addLand operation which turns the water at position (row, col) into a land. Given a list of positions to operate, count the number of islands after each addLand o…

In this problem, a tree is an undirected graph that is connected and has no cycles. The given input is a graph that started as a tree with N nodes (with distinct values 1, 2, ..., N), with one additional edge added. The added edge has two different v…

Leetcode之并查集专题-684. 冗余连接(Redundant Connection) 在本问题中, 树指的是一个连通且无环的无向图. 输入一个图,该图由一个有着N个节点 (节点值不重复1, 2, ..., N) 的树及一条附加的边构成.附加的边的两个顶点包含在1到N中间,这条附加的边不属于树中已存在的边. 结果图是一个以边组成的二维数组.每一个边的元素是一对[u, v] ,满足 u < v,表示连接顶点u 和v的无向图的边. 返回一条可以删去的边,使得结果图是一个有着N个节点的树.如果有…

[1]LeetCode 136 Single Number 题意:奇数个数,其中除了一个数只出现一次外,其他数都是成对出现,比如1,2,2,3,3...,求出该单个数. 解法:容易想到异或的性质,两个相同的数异或为0,那么把这串数从头到尾异或起来,最后的数就是要求的那个数. 代码如下: class Solution { public: int singleNumber(vector<int>& nums) { ; ;i<nums.size();i++) sum ^= nums[i…

leetcode - 40. Combination Sum II - Medium descrition Given a collection of candidate numbers (C) and a target number (T), find all unique combinations in C where the candidate numbers sums to T. Each number in C may only be used once in the combinat…

LeetCode 137. Single Number II(只出现一次的数字 II)…

LeetCode:路径总和II[113] 题目描述 给定一个二叉树和一个目标和,找到所有从根节点到叶子节点路径总和等于给定目标和的路径. 说明: 叶子节点是指没有子节点的节点. 示例:给定如下二叉树,以及目标和 sum = 22, 5 / \ 4 8 / / \ 11 13 4 / \ / \ 7 2 5 1 返回: [ [5,4,11,2], [5,8,4,5] ] 题目分析 首先是一个深度搜索,来把所有根节点到叶子节点的路径找出来,然后各自判断是否等于目标值,等于目标值的路径加入结果集中.这…

LeetCode:组合总数II[40] 题目描述 给定一个数组 candidates 和一个目标数 target ,找出 candidates 中所有可以使数字和为 target 的组合. candidates 中的每个数字在每个组合中只能使用一次. 说明: 所有数字(包括目标数)都是正整数. 解集不能包含重复的组合. 示例 1: 输入: candidates = [10,1,2,7,6,1,5], target = 8, 所求解集为: [ [1, 7], [1, 2, 5], [2, 6],…

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 并查集 日期 题目地址:https://leetcode.com/problems/redundant-connection/description/ 题目描述 In this problem, a tree is an undirected graph that is connected and has no cycles. The given i…

其他LeetCode题目欢迎访问:LeetCode结题报告索引 LeetCode:Word Ladder Given two words (start and end), and a dictionary, find the length of shortest transformation sequence from start to end, such that: Only one letter can be changed at a time Each intermediate word…

LeetCode:Path Sum Given a binary tree and a sum, determine if the tree has a root-to-leaf path such that adding up all the values along the path equals the given sum. For example:Given the below binary tree and sum = 22, 5 / \ 4 8 / / \ 11 13 4 / \ \…

Work Break I Given a string s and a dictionary of words dict, determine if s can be segmented into a space-separated sequence of one or more dictionary words. For example, givens = "leetcode",dict = ["leet", "code"]. Return t…

原题链接在这里:Majority Element I,Majority Element II 对于Majority Element I 来说,有多重解法. Method 1:最容易想到的就是用HashMap 计数,数值大于n/2(注意不是大于等于而是大于),就是返回值.Time O(n), Space O(n). Method 2: 用了sort,返回sort后array的中值即可.Time O(n*logn), Space O(1). Method 3: 维护个最常出现值,遇到相同count+…

一. 题目 1. Two Sum II Given an array of integers that is already sorted in ascending order, find two numbers such that they add up to a specific target number. The function twoSum should return indices of the two numbers such that they add up to the ta…

I title: https://leetcode.com/problems/word-break/ Given a string s and a dictionary of words dict, determine if s can be segmented into a space-separated sequence of one or more dictionary words. For example, givens = "leetcode",dict = ["l…

Title: https://leetcode.com/problems/unique-paths/ A robot is located at the top-left corner of a m x n grid (marked 'Start' in the diagram below). The robot can only move either down or right at any point in time. The robot is trying to reach the bo…

# -*- coding: utf8 -*-'''__author__ = 'dabay.wang@gmail.com' 52: N-Queens IIhttps://oj.leetcode.com/problems/n-queens-ii/ Follow up for N-Queens problem.Now, instead outputting board configurations, return the total number of distinct solutions. ===C…

# -*- coding: utf8 -*-'''__author__ = 'dabay.wang@gmail.com' 47: Permutations IIhttps://oj.leetcode.com/problems/permutations-ii/ Given a collection of numbers that might contain duplicates, return all possible unique permutations. For example,[1,1,2…

[题目] Given a collection of candidate numbers (candidates) and a target number (target), find all unique combinations in candidates where the candidate numbers sums to target. Each number in candidates may only be used once in the combination. Note: A…