Given a binary search tree (BST), find the lowest common ancestor (LCA) of two given nodes in the BST. According to the definition of LCA on Wikipedia: “The lowest common ancestor is defined between t

Implement the following operations of a queue using stacks. push(x) -- Push element x to the back of queue. pop() -- Removes the element from in front of queue. peek() -- Get the front element. empty(

Given an integer n, count the total number of digit 1 appearing in all non-negative integers less than or equal to n. Example: Input: 13 Output: 6 Explanation: Digit 1 occurred in the following num

Write an efficient algorithm that searches for a value in an m x n matrix. This matrix has the following properties: Integers in each row are sorted in ascending from left to right. Integers in each c

Given an array nums of n integers where n > 1,  return an array outputsuch that output[i] is equal to the product of all the elements of numsexcept nums[i]. Example: Input: Output: [1,2,3,4][24,1

Given an array nums, there is a sliding window of size k which is moving from the very left of the array to the very right. You can only see the k numbers in the window. Each time the sliding window m

本文将演示监听屏幕上触摸事件的各种状态。 在项目导航区，打开视图控制器的代码文件【ViewController.swift】 现在开始编写代码，监听屏幕上的触摸事件的各种状态。 1 import UIKit 2 3 class ViewController: UIViewController { 4 5 override func viewDidLoad() {

本文将演示通过捏合手势，实现图片的放大和缩小。 在项目导航区，打开视图控制器的代码文件【ViewController.swift】 现在开始编写代码，实现通过捏合手势，实现图片的放大和缩小。 1 import UIKit 2 3 class ViewController: UIViewController { 4 5 override func viewDid

本文将演示3DTouch三维触摸手势的使用。 双卡双待的iPhone XR中，苹果取消了3DTouch功能。 在项目导航区，打开应用程序的代理文件【AppDelegate.swift】 当三维触摸手势被触发时，将在应用程序的图标位置显示一个菜单列表， 现在从创建这个菜单列表开始。 1 import UIKit 2 3 @UIApplicationMain 4 class AppDe

本文将演示监听手势事件，使图片可以自由被拖动。 在项目导航区，打开视图控制器的代码文件【ViewController.swift】 现在开始编写代码，实现监听手势事件自由拖动的图像视图。 1 import UIKit 2 3 class ViewController: UIViewController 4 { 5 //给类添加一个属性，作为被拖动的图像视图。 6

本文将演示如何制作五彩缤纷的气泡图表。 首先确保在项目中已经安装了所需的第三方库。 点击【Podfile】,查看安装配置文件。 1 platform :ios, ‘12.0‘ 2 use_frameworks! 3 4 target ‘DemoApp‘ do 5 source ‘https://github.com/CocoaPods/Specs.git‘ 6 pod

本文将演示如何制作股市中常用的蜡烛图表。 首先确保在项目中已经安装了所需的第三方库。 点击【Podfile】,查看安装配置文件。 1 platform :ios, ‘12.0‘ 2 use_frameworks! 3 4 target ‘DemoApp‘ do 5 source ‘https://github.com/CocoaPods/Specs.git‘ 6 pod

本文将演示如何创建复合图表：包含线性图表和柱形图表。 首先确保在项目中已经安装了所需的第三方库。 点击【Podfile】,查看安装配置文件。 1 platform :ios, ‘12.0‘ 2 use_frameworks! 3 4 target ‘DemoApp‘ do 5 source ‘https://github.com/CocoaPods/Specs.git‘ 6

本文将演示如何创建雷达图表更加形象表示各个维度的情况。 首先确保在项目中已经安装了所需的第三方库。 点击【Podfile】,查看安装配置文件。 1 platform :ios, ‘12.0‘ 2 use_frameworks! 3 4 target ‘DemoApp‘ do 5 source ‘https://github.com/CocoaPods/Specs.git‘ 6

本文将演示如何使用第三方库实现网络请求服务。 首先确保在项目中已经安装了所需的第三方库。 点击【Podfile】,查看安装配置文件。 1 source ‘https://github.com/CocoaPods/Specs.git‘ 2 platform :ios, ‘12.0‘ 3 use_frameworks! 4 5 target ‘DemoApp’ do 6 pod ‘

本文将演示如何使用Alamofire验证请求结果和可访问性。 首先确保在项目中已经安装了所需的第三方库。 点击【Podfile】,查看安装配置文件。 1 source ‘https://github.com/CocoaPods/Specs.git‘ 2 platform :ios, ‘12.0‘ 3 use_frameworks! 4 5 target ‘DemoApp’ do 6

本文将演示下载网络图片，显示下载进度，并保存在沙箱目录中。 首先确保在项目中已经安装了所需的第三方库。 点击【Podfile】,查看安装配置文件。 1 source ‘https://github.com/CocoaPods/Specs.git‘ 2 platform :ios, ‘12.0‘ 3 use_frameworks! 4 5 target ‘DemoApp’ do 6

Numbers can be regarded as product of its factors. For example, 8 = 2 x 2 x 2; = 2 x 4. Write a function that takes an integer n and return all possible combinations of its factors. Note:  Each c

There are a row of n houses, each house can be painted with one of the three colors: red, blue or green. The cost of painting each house with a certain color is different. You have to paint all the ho

import UIKit var imageView:UIImageView! class ViewController: UIViewController { override func viewDidLoad() { super.viewDidLoad() //创建ImageView imageView = UIImageView(fra

import UIKit class ViewController: UIViewController { override func viewDidLoad() { super.viewDidLoad() //创建UITextView let textView = UITextView(frame: CGRect(x: 10, y: 1

import UIKit class ViewController: UIViewController,UITextFieldDelegate { var textField:UITextField!//声明一个UItextField类型变量 override func viewDidLoad() { super.viewDidLoad() //创

import UIKit class ViewController: UIViewController { override func viewDidLoad() { super.viewDidLoad() //创建UISWitch(Switch无需设置大小) let uiSwitch = UISwitch(frame: CGRect(x:

mport UIKit class ViewController: UIViewController { override func viewDidLoad() { super.viewDidLoad() //创建Button类型：system,custom,contactAdd,(detailDisclosure,infoDark,infoLight效

Given n nodes labeled from 0 to n - 1 and a list of undirected edges (each edge is a pair of nodes), write a function to check whether these edges make up a valid tree. For example: Given n = 5 and ed

import UIKit var imageView:UIImageView! class ViewController: UIViewController { override func viewDidLoad() { super.viewDidLoad() //创建ProgressView let progressView = UIPro

import UIKit class ViewController: UIViewController { override func viewDidLoad() { super.viewDidLoad() let items = ["optionA","optionB","optionC"] let segmented = UISegme

import UIKit var imageView:UIImageView! class ViewController: UIViewController { override func viewDidLoad() { super.viewDidLoad() //创建Slider let slider = UISlider(frame: C

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 powerful integers that have value less than or equ

Given an array A, we can perform a pancake flip: We choose some positive integer k <= A.length, then reverse the order of the first k elements of A.  We want to perform zero or more pancake flips (doi