207. 课程表 现在你总共有 n 门课需要选,记为 0 到 n-1. 在选修某些课程之前需要一些先修课程. 例如,想要学习课程 0 ,你需要先完成课程 1 ,我们用一个匹配来表示他们: [0,1] 给定课程总量以及它们的先决条件,判断是否可能完成所有课程的学习? 示例 1: 输入: 2, [[1,0]] 输出: true 解释: 总共有 2 门课程.学习课程 1 之前,你需要完成课程 0.所以这是可能的. 示例 2: 输入: 2, [[1,0],[0,1]] 输出: false 解释: 总共有…

There are a total of n courses you have to take, labeled from 0 to n - 1. Some courses may have prerequisites, for example to take course 0 you have to first take course 1, which is expressed as a pair: [0,1] Given the total number of courses and a l…

课程表 现在你总共有 n 门课需要选,记为 0 到 n-1. 在选修某些课程之前需要一些先修课程. 例如,想要学习课程 0 ,你需要先完成课程 1 ,我们用一个匹配来表示他们: [0,1] 给定课程总量以及它们的先决条件,判断是否可能完成所有课程的学习? 示例 1: 输入: 2, [[1,0]] 输出: true 解释: 总共有 2 门课程.学习课程 1 之前,你需要完成课程 0.所以这是可能的. 示例 2: 输入: 2, [[1,0],[0,1]] 输出: false 解释: 总共有 2 门课…

630. 课程表 III 这里有 n 门不同的在线课程,他们按从 1 到 n 编号.每一门课程有一定的持续上课时间(课程时间)t 以及关闭时间第 d 天.一门课要持续学习 t 天直到第 d 天时要完成,你将会从第 1 天开始. 给出 n 个在线课程用 (t, d) 对表示.你的任务是找出最多可以修几门课. 示例: 输入: [[100, 200], [200, 1300], [1000, 1250], [2000, 3200]] 输出: 3 解释: 这里一共有 4 门课程, 但是你最多可以修 3…

210. 课程表 II 现在你总共有 n 门课需要选,记为 0 到 n-1. 在选修某些课程之前需要一些先修课程. 例如,想要学习课程 0 ,你需要先完成课程 1 ,我们用一个匹配来表示他们: [0,1] 给定课程总量以及它们的先决条件,返回你为了学完所有课程所安排的学习顺序. 可能会有多个正确的顺序,你只要返回一种就可以了.如果不可能完成所有课程,返回一个空数组. 示例 1: 输入: 2, [[1,0]] 输出: [0,1] 解释: 总共有 2 门课程.要学习课程 1,你需要先完成课程 0.因…

题目 现在你总共有 n 门课需要选,记为 0 到 n-1. 在选修某些课程之前需要一些先修课程. 例如,想要学习课程 0 ,你需要先完成课程 1 ,我们用一个匹配来表示他们: [0,1] 给定课程总量以及它们的先决条件,判断是否可能完成所有课程的学习? 示例 1: 输入: 2, [[1,0]] 输出: true 解释: 总共有 2 门课程.学习课程 1 之前,你需要完成课程 0.所以这是可能的. 示例 2: 输入: 2, [[1,0],[0,1]] 输出: false 解释: 总共有 2 门课程…

class Solution { public: bool canFinish(int numCourses, vector<vector<int>>& prerequisites) { //验证是否为DAG,每次验证指向的是否已经存在于当前图中 //建图 vector<);//入度 vector<vector<,));//邻接表 ;i<prerequisites.size();i++){ indegree[prerequisites[i][]]++…

There are a total of n courses you have to take, labeled from 0 to n - 1. Some courses may have prerequisites, for example to take course 0 you have to first take course 1, which is expressed as a pair: [0,1] Given the total number of courses and a l…

LeetCode:课程表[207] 题目描述 现在你总共有 n 门课需要选,记为 0 到 n-1. 在选修某些课程之前需要一些先修课程. 例如,想要学习课程 0 ,你需要先完成课程 1 ,我们用一个匹配来表示他们: [0,1] 给定课程总量以及它们的先决条件,判断是否可能完成所有课程的学习? 示例 1: 输入: 2, [[1,0]] 输出: true 解释: 总共有 2 门课程.学习课程 1 之前,你需要完成课程 0.所以这是可能的. 示例 2: 输入: 2, [[1,0],[0,1]] 输出:…

LeetCode:课程表II[210] 题目描述 现在你总共有 n 门课需要选,记为 0 到 n-1. 在选修某些课程之前需要一些先修课程. 例如,想要学习课程 0 ,你需要先完成课程 1 ,我们用一个匹配来表示他们: [0,1] 给定课程总量以及它们的先决条件,返回你为了学完所有课程所安排的学习顺序. 可能会有多个正确的顺序,你只要返回一种就可以了.如果不可能完成所有课程,返回一个空数组. 示例 1: 输入: 2, [[1,0]] 输出: [0,1] 解释: 总共有 2 门课程.要学习课程 1…

Find all possible combinations of k numbers that add up to a number n, given that only numbers from 1 to 9 can be used and each combination should be a unique set of numbers. Ensure that numbers within the set are sorted in ascending order. Example 1…

Given a string S, you are allowed to convert it to a palindrome by adding characters in front of it. Find and return the shortest palindrome you can find by performing this transformation. For example: Given "aacecaaa", return "aaacecaaa&qu…

Given a 2D board and a list of words from the dictionary, find all words in the board. Each word must be constructed from letters of sequentially adjacent cell, where "adjacent" cells are those horizontally or vertically neighboring. The same le…

Design a data structure that supports the following two operations: void addWord(word)bool search(word) search(word) can search a literal word or a regular expression string containing only letters a-z or .. A . means it can represent any one letter.…

Given a 2d grid map of '1's (land) and '0's (water), count the number of islands. An island is surrounded by water and is formed by connecting adjacent lands horizontally or vertically. You may assume all four edges of the grid are all surrounded by…

Say you have an array for which the ith element is the price of a given stock on day i. Design an algorithm to find the maximum profit. You may complete at most k transactions. 解题思路: https://leetcode.com/discuss/18330/is-it-best-solution-with-o-n-o-1…

Suppose a sorted array is rotated at some pivot unknown to you beforehand. (i.e., 0 1 2 4 5 6 7 might become 4 5 6 7 0 1 2). Find the minimum element. The array may contain duplicates. 解题思路: 参考Java for LeetCode 081 Search in Rotated Sorted Array II J…

Suppose a sorted array is rotated at some pivot unknown to you beforehand. (i.e., 0 1 2 4 5 6 7 might become 4 5 6 7 0 1 2). Find the minimum element. You may assume no duplicate exists in the array. 解题思路: 本题和Java for LeetCode 033 Search in Rotated S…

The set [1,2,3,…,n] contains a total of n! unique permutations. By listing and labeling all of the permutations in order, We get the following sequence (ie, for n = 3): "123" "132" "213" "231" "312" "…

Given an integer n, generate a square matrix filled with elements from 1 to n2 in spiral order. For example, Given n = 3, You should return the following matrix: [ [ 1, 2, 3 ], [ 8, 9, 4 ], [ 7, 6, 5 ]] 解题思路: 参考Java for LeetCode 054 Spiral Matrix,修改下…

Given a set of non-overlapping intervals, insert a new interval into the intervals (merge if necessary). You may assume that the intervals were initially sorted according to their start times. Example 1: Given intervals [1,3],[6,9], insert and merge…

Given an array of non-negative integers, you are initially positioned at the first index of the array. Each element in the array represents your maximum jump length at that position. Determine if you are able to reach the last index. For example: A =…

Given a collection of numbers that might contain duplicates, return all possible unique permutations. For example, [1,1,2] have the following unique permutations: [1,1,2], [1,2,1], and [2,1,1]. 解题思路一: 发现Java for LeetCode 046 Permutations自己想多了,代码直接拿来用…

Implement wildcard pattern matching with support for '?' and '*'. '?' Matches any single character. '*' Matches any sequence of characters (including the empty sequence). The matching should cover the entire input string (not partial). The function p…

Given a string containing just the characters '(' and ')', find the length of the longest valid (well-formed) parentheses substring. For "(()", the longest valid parentheses substring is "()", which has length = 2. Another example is &…

Merge k sorted linked lists and return it as one sorted list. Analyze and describe its complexity. 解题思路一: 之前我们有mergeTwoLists(ListNode l1, ListNode l2)方法,直接调用的话,需要k-1次调用,每次调用都需要产生一个ListNode[],空间开销很大.如果采用分治的思想,对相邻的两个ListNode进行mergeTwoLists,每次将规模减少一半,直到…

A linked list is given such that each node contains an additional random pointer which could point to any node in the list or null. Return a deep copy of the list. 解题思路: 我们在Java for LeetCode 133 Clone Graph题中做过图的复制,本题和图的复制十分类似,JAVA实现如下: public Random…

Given an unsorted array of integers, find the length of the longest consecutive elements sequence. For example, Given [100, 4, 200, 1, 3, 2], The longest consecutive elements sequence is [1, 2, 3, 4]. Return its length: 4. Your algorithm should run i…

Given two words (start and end), and a dictionary, find all shortest transformation sequence(s) from start to end, such that: Only one letter can be changed at a time    Each intermediate word must exist in the dictionary For example, Given:start = "…

Say you have an array for which the ith element is the price of a given stock on day i. If you were only permitted to complete at most one transaction (ie, buy one and sell one share of the stock), design an algorithm to find the maximum profit. 解题思路…