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编写一个高效的算法来搜索mxn矩阵 matrix 中的一个目标值 target。该矩阵具有以下特性：每行的元素从左到右升序排列。每列的元素从上到下升序排列。示例:现有矩阵 matrix 如下：[ [1, 4, 7, 11, 15], [2, 5, 8, 12, 19], [3, 6, 9, 16, 22], [10, 13, 14, 17,...

在一个由 0 和 1 组成的二维矩阵内，找到只包含 1 的最大正方形，并返回其面积。示例:输入:1 0 1 0 01 0 1 1 11 1 1 1 11 0 0 1 0输出: 4class Solution { public int maximalSquare(char[][] matrix) { int m = matrix.length;...

Given a string s, partition s such that every substring of the partition is a palindrome.Return the minimum cuts needed for a palindrome partitioning of s.Example:Input: "aab"Output: 1Explana...

Given a reference of a node in a connected undirected graph, return a deep copy (clone) of the graph. Each node in the graph contains a val (int) and a list (List[Node]) of its neighbors. Example...

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 pai...

Implement a trie with insert, search, and startsWith methods.Example:Trie trie = new Trie();trie.insert("apple");trie.search("apple"); // returns truetrie.search("app"); // returns fals...

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 pai...

There are N gas stations along a circular route, where the amount of gas at station i is gas[i].You have a car with an unlimited gas tank and it costs cost[i] of gas to travel from station i to its...

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...

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 hori...

待续。。。找时间攻克KMP算法。。。

Find the kth largest element in an unsorted array. Note that it is the kth largest element in the sorted order, not the kth distinct element.Example 1:Input: [3,2,1,5,6,4] and k = 2Output: 5Exa...

According to the Wikipedia's article: "The Game of Life, also known simply as Life, is a cellular automaton devised by the British mathematician John Horton Conway in 1970."Given a board with m by ...

Given an array of integers, 1 ≤ a[i] ≤ n (n = size of array), some elements appear twice and others appear once.Find all the elements that appear twice in this array.Could you do it without extra...

You are given a circular array nums of positive and negative integers. If a number k at an index is positive, then move forward k steps. Conversely, if it's negative (-k), move backward k steps. Sinc...

A zero-indexed array A of length N contains all integers from 0 to N-1. Find and return the longest length of set S, where S[i] = {A[i], A[A[i]], A[A[A[i]]], ... } subjected to the rule below.Suppo...

Given a string s, partition s such that every substring of the partition is a palindrome.Return all possible palindrome partitioning of s.Example:Input: "aab"Output:[ ["aa","b"], ["a","a"...

待续。。。

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 assum...

Given a list of 24-hour clock time points in "Hour:Minutes" format, find the minimum minutes difference between any two time points in the list.Example 1:Input: ["23:59","00:00"]Output: 1Note:The nu...

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.Your goal is t...

Given a string S and a string T, find the minimum window in S which will contain all the characters in T in complexity O(n).Example:Input: S = "ADOBECODEBANC", T = "ABC"Output: "BANC"Note:If ...

Given a non-empty string s and a dictionary wordDict containing a list of non-empty words, determine if s can be segmented into a space-separated sequence of one or more dictionary words.Note:The...

Given a non-empty string s and a dictionary wordDict containing a list of non-empty words, add spaces in s to construct a sentence where each word is a valid dictionary word. Return all such possible...

Sort a linked list in O(n log n) time using constant space complexity.Example 1:Input: 4->2->1->3Output: 1->2->3->4Example 2:Input: -1->5->3->4->0Output: -1-&gt...

A peak element is an element that is greater than its neighbors.Given an input array nums, where nums[i] ≠ nums[i+1], find a peak element and return its index.The array may contain multiple peaks...

待续。。。太难了。。。

Table: Person+-------------+---------+| Column Name | Type |+-------------+---------+| PersonId | int || FirstName | varchar || LastName | varchar |+-------------+---------+Pe...

Write a SQL query to get the second highest salary from the Employee table.+----+--------+| Id | Salary |+----+--------+| 1 | 100 || 2 | 200 || 3 | 300 |+----+--------+For exampl...

Write a SQL query to get the nth highest salary from the Employee table.+----+--------+| Id | Salary |+----+--------+| 1 | 100 || 2 | 200 || 3 | 300 |+----+--------+For example, ...

Write a SQL query to rank scores. If there is a tie between two scores, both should have the same ranking. Note that after a tie, the next ranking number should be the next consecutive integer value....

Write a SQL query to find all numbers that appear at least three times consecutively.+----+-----+| Id | Num |+----+-----+| 1 | 1 || 2 | 1 || 3 | 1 || 4 | 2 || 5 | 1 || 6 | ...

Given two words (beginWord and endWord), and a dictionary's word list, find all shortest transformation sequence(s) from beginWord to endWord, such that:Only one letter can be changed at a timeEac...

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.Note:You may not en...

这是一道关于二叉树树的题目，题目的本质是进行遍历各节点。代码如下：class Solution(object): def Get_Sum(self, root, n): if not root: return 0 if not root.left and not root.right: return n