We are given two arrays A and B of words.  Each word is a string of lowercase letters. Now, say that word b is a subset of word a if every letter in b occurs in a, including multiplicity.  For example

Given a string, find the length of the longest substring without repeating characters. Examples: Given "abcabcbb", the answer is "abc", which the length is 3. Given "bbbbb", the answer is "b", with th

1、二叉树的特点： (1)、每个节点最多有两个子树 (2)、左子树和右子树是有顺序的，次序不能颠倒 (3)、即使某节点只有一个子树，也要区分左右子树 2、二叉查找树（Binary Search Tree）:（又：二叉搜索树，二叉排序树） (1)、它或者是一棵空树，或者是具有下列性质的二叉树： 若它的左子树不空，则左子树上所有结点的值均小于它的根结点的值； 若它的右子树不空，则右子树上所有结点的值均

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

Every email consists of a local name and a domain name, separated by the @ sign. For example, in [email protected], alice is the local name, and leetcode.com is the domain name. Besides lowercase lett

Given a square array of integers A, we want the minimum sum of a falling path through A. A falling path starts at any element in the first row, and chooses one element from each row.  The next row‘s c

本文将给项目中的所有视图控制器，创建一份基类。该基类用来定义一些共用的属性和方法。 首先在用来放置视图控制器类的文件夹上点击鼠标右键，打开右键 菜单。 选择【New File】创建文件选项。 在弹出的文件模板选择窗口中，保持默认的选项， 然后点击【Next】下一步按钮，进入下一步设置页面。输入类名、父类、语言 【Class】:BaseViewController 【Subclass】:UIView

LeetCode Solution Summary | LeetCode解题汇总 序号[#] 题名[Title] 通过率[Acceptance] 难度[Difficulty] 1       2       3       4       5       6       7       8       9       10       11       12       13       14  

Determine if a 9x9 Sudoku board is valid. Only the filled cells need to be validated according to the following rules: Each row must contain the digits 1-9 without repetition. Each column must contain

 Write a program to solve a Sudoku puzzle by filling the empty cells. A sudoku solution must satisfy all of the following rules: Each of the digits 1-9 must occur exactly once in each row. Each of the

Given a set of candidate numbers (candidates) (without duplicates) and a target number (target), find all unique combinations in candidates where the candidate numbers sums to target. The same repeate

1 import UIKit 2 3 class WelcomeViewController: BaseViewController { 4 5 override func viewDidLoad() { 6 super.viewDidLoad() 7 8 // Do any additional se

Given n non-negative integers representing an elevation map where the width of each bar is 1, compute how much water it is able to trap after raining. The above elevation map is represented by array [

Character转ASCII整数值： 1 //Character扩展方法 2 extension Character 3 { 4 //属性：ASCII整数值(定义小写为整数值) 5 var ascii: Int { 6 get { 7 let s = String(self).unicodeScalars

Write a class RecentCounter to count recent requests. It has only one method: ping(int t), where t represents some time in milliseconds. Return the number of pings that have been made from 3000 millis

A chess knight can move as indicated in the chess diagram below:  .              This time, we place our chess knight on any numbered key of a phone pad (indicated above), and the knight makes N-1 hop

Given an input string (s) and a pattern (p), implement wildcard pattern matching with support for ‘?‘ and ‘*‘. ‘?‘ Matches any single character. ‘*‘ Matches any sequence of characters (including the

You are given an n x n 2D matrix representing an image. Rotate the image by 90 degrees (clockwise). Note: You have to rotate the image in-place, which means you have to modify the input 2D matrix dire

The n-queens puzzle is the problem of placing n queens on an n×n chessboard such that no two queens attack each other. Given an integer n, return the number of distinct solutions to the n-queens puzzl

Given a matrix of m x n elements (m rows, n columns), return all elements of the matrix in spiral order. Example 1: Input: [ [ 1, 2, 3 ], [ 4, 5, 6 ], [ 7, 8, 9 ] ] Output: [1,2,3,6,9,8,7,4,5

  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 b

Given a m x n grid filled with non-negative numbers, find a path from top left to bottom right which minimizes the sum of all numbers along its path. Note: You can only move either down or right at an

Given an array of words and a width maxWidth, format the text such that each line has exactly maxWidth characters and is fully (left and right) justified. You should pack your words in a greedy approa

设计问题：谁来构造、构造什么、怎么添加新功能   关键词：本体、客体、构造、映射、功能。 别名：桥接变量、型变变量、容器变量、适配变量，构造变量； 目的：添加命名空间、添加新功能。 原则：不修改本体的实现。   原始版本： 在本体的扩展中，直接构造客体；客体的构造器输入参量为主体； 客体为具体类，直接完成本体想要完成的功能；   版本升级一：客体泛型化 目的：客体的功能实现脱离 // 客体 pub

Given a m x n matrix, if an element is 0, set its entire row and column to 0. Do it in-place. Example 1: Input: [   [1,1,1],   [1,0,1],   [1,1,1] ] Output: [   [1,0,1],   [0,0,0],   [1,0,1

Given a 2D board and a word, find if the word exists in the grid. The word can be constructed from letters of sequentially adjacent cell, where "adjacent" cells are those horizontally or vertically ne

1 import Foundation 2 3 enum Validate { 4 case email(_: String) // 邮箱 5 case phoneNum(_: String) // 手机 6 case carNum(_: String) // 车牌号 7 case username(_: Str

Given a sorted linked list, delete all nodes that have duplicate numbers, leaving only distinct numbers from the original list. Example 1: Input: 1->2->3->3->4->4->5 Output: 1->2->5 Example 2: Inpu

A message containing letters from A-Z is being encoded to numbers using the following mapping: ‘A‘ -> 1 ‘B‘ -> 2 ... ‘Z‘ -> 26 Given a non-empty string containing only digits, determine the total

Given an integer n, generate all structurally unique BST‘s (binary search trees) that store values 1 ... n. Example: Input: 3 Output: [   [1,null,3,2],   [3,2,null,1],   [3,1,null,null,2],   [2,