Articles
AI

Mo team algorithm

ACM template Mo team algorithm It can solve a class of static and offline interval query problems. Reference topic link: BZOJ 2038 [2009 National Training Team] Little Z's hose problem solution: only need to count the square sum of the number of occurrences in the interval. Mo team algorithm, two methods, one is directly divided into sqrt (n) block, block sorting. The other is to obtain the minimum spanning tree of Manhattan distance, which is solved according to the dfs order of Manhattan MST.

... Luke
schedule 8 min read
AI

Discussion on several situations of RTMP multi-instance push on Android platform

Many developers mentioned how to implement Android platform, multi-instance push, multi-instance push, there are several understandings: Multi-channel encoding, multiple instances are pushed to different RTMP URLs (for example, the Android capture board is connected to 2 channels at the same time); With the same encoding, multiple instances are pushed to different RTMP URLs (for example, pushed to different RTMP servers on the intranet and extranet); Multiple instances of H.264/AAC data after pa

... Bryce
schedule 7 min read
AI

Data Mining Notes Technical Chapter-Chapter5 Classification Algorithm KNN

Build a classifier based on relative distance measurements Among them, the most representative is the KNN algorithm Reference: "Principles of Statistical Learning Li Hang" 1. Introduction to KNN algorithm data set: T=[(x1,y1),(x2,y2),...,(xn,yn)]T={[(x_1,y_1),(x_2,y_2),...,(x_n,y_n)]}T=[ ( x1,y1) ,( x2,y2) ,. . . ,( xn,yn) ] among them xiAXARnx_i \in \mathcal{X} \in \mathbb{R}^nxiAXARn is the feature vector of the instance, yiAY=[c1,c2,...,cN]y_i \in \mathcal{Y}=[c_1,c_2,...,c_N]yiAY=[ c1,c2,. .

... Angel
schedule 5 min read
AI

Java basics: basic knowledge

Contents: 1. Java overview 1. Java system 2. Commonly used DOS commands 3. JDK, JRE, cross-platform, Java platform 4. Java code writing and execution process 5. Notes 6. Keywords, identifiers 7. Java Data type 8. Constants in Java 2. Variables and operators 1. Variables and computer storage units 2. Data types and constants 3. Data type conversion 4. Operators and precedence 3. Reference data types, flow control statements and arrays 1. Reference data type 2. Flow control statement 3. Array 4.

... Ayden
schedule 23 min read
Android

Coil and Glide's Bitmap cache reuse mechanism

Official account : byte array , I hope to help you The most familiar image loading framework for Android developers should be Glide and Picasso. In the past two years, there has also been a rising star: Coil Coil is an emerging Android image loading library. The name of Coil comes from: Co routine, I mage and L oader get Coil. Its characteristics are: Faster : Coil has made many optimizations in performance, including memory caching and disk caching, sampling images in memory, reusing Bitmap, a

... Landon
schedule 25 min read
Android

ASM instrumentation-multi-threaded operation monitoring

Recently, it is necessary to optimize the startup time of the App. The existing code has the following problems: Threads are not reused (using new Thread\HandlerThread), creating too many threads Use HandlerThread, not destroyed after use (Looper has been waiting), occupying memory Start thread early, but not used Some business parties initialize business code prematurely (although asynchronous), which affects startup time Due to the above problems, it is necessary to scan the execution of the s

... Hudson
schedule 18 min read
Android

Android Rxjava3

Study notes (4) Detailed explanation of Rxjava3 and its use in Android: basic concepts Add dependency: Implementation 'io.reactivex.rxjava3: rxjava: 3.0.13' Implementation 'io.reactivex.rxjava3: rxandroid: 3.0.0' Copy Code Add java8 compilation compileOptions { sourceCompatibility JavaVersion.VERSION_1_8 targetCompatibility JavaVersion.VERSION_1_8 } Copy code 1), basic concepts RxJava is a java implementation of Reactive Extensions, which implements an asynchronous programming interface based on

... Ashley
schedule 15 min read
Android

Interview

Containers used in development Arraylist The bottom layer is an array Expansion mechanism: The default expansion is half. If half of the expansion is not enough, use the target size (original array length + 1) as the expanded capacity In the process of adding, deleting, modifying, and checking, if the addition leads to expansion, modCount will be modified, and the deletion will definitely be modified. Changing and checking will definitely not modify modCount. Expansion operations will result in

... Dominic
schedule 69 min read
Back End

In-depth understanding of the synchronized keyword

Preface The importance of the synchronized keyword is self-evident, it can almost be said that it is a keyword that must be asked for concurrent and multithreaded. Synchronized will involve locks, upgrade and downgrade operations, lock revocation, object headers, etc. Therefore, it is very important to understand synchronization. This article will take you from the basic usage of synchronized to the in-depth understanding of synchronized and the first class of objects, and uncover the veil of sy

... Kaylee
schedule 21 min read
Back End

Recommend to everyone a Thinkphp rich text editor that is easy to use with fried chicken

Introduction: Recently, I have been doing Thinkphp back-end development. I used to use layui's rich text editor. The advantage of layui is that it is simple and easy to use, but the disadvantage is also obvious. It is that the editor has relatively few functions, and I accidentally found it used in other people s projects. It is a rich text editor of CKEditor, and it feels so generous! Let's learn how to use CKEditor together Ckeditor4 download address (the CKEditor 4.16 version selected for thi

... Wesley
schedule 8 min read
Back End

In-depth analysis of spring source code spring integration mybatis principle analysis and spring extension point analysis

Preface I recently watched a video about how to interview. It said that you should not just write that you have read the source code of XX, but reflect it in the project. Even if you don t have it in your own project, you can say that you have seen it in other people s projects. Some features of a certain framework, so I am ready to try it myself to learn the essence of an excellent framework, I manually integrated spring and mybatis, and the view to experience the excellence of mybatis. begin T

... Kaden
schedule 17 min read
Back End

Android program version detection and update

Be an Android client of a website, and the user installs it on his mobile phone. What if I release a new version? There must be a version update function. Originally, version detection is best done automatically. But if you start the program every time, you must first check it, which is a waste. After all, version updates are a small probability thing. Maybe you can judge the time when the program is started. It will be tested on a single day, but not tested on two days, or randomly, to reduce t

... Molly
schedule 9 min read
Front End

Detailed explanation of the principle of onion model of node framework koa2

Koa - Next-generation web development framework based on Node.js platform koa2 was created by the original team of Express, and is committed to becoming a smaller, more expressive, and more robust Web framework. Use koa writing web applications, eliminating duplication of tedious callback function nesting, and greatly enhance the efficiency of error handling. koa kernel method is not bound to any middleware , it only provides a lightweight and elegant library, makes writing Web applications beco

... Alejandro
schedule 9 min read
Front End

Implement tree component based on react + typescript

based on react + typescript achieve tree Component github Support unit testing Support open and close Support unselect all Support dynamic loading Support drag sort process line 1.1 Create a project and install dependencies 1.2 webpack configuration initialization, support typescript 2.1 Unit test environment construction Create tree menu Create tree menu 5.1 Turn on and off the function-icons 5.2 Turn on and off the function-keyToNodeMap 5.3 Open and close function-images.d.ts image type declar

... Justin
schedule 13 min read
Front End

[vue] Worry-saving and labor-saving skeleton screen 2, list skeleton screen

vue3 skeleton screen + pull up to load more packages Foreword, introduction The skeleton screen of this list had an initial version before, and I wrote a blog once, but it was posted on the csdn, and then changed once, because the reading volume of that blog post was not high, and there was no motivation to update it. The main difference between the first version and the current version is that the implementation idea is different. Before, the skeleton screen was used as a module, and then the s

... Bennett
schedule 16 min read
Front End

"React series dry goods under" (must know and know)

This article is a continuation of "React Series Dry Goods Part 1". Because of the upper word limit, I opened it. The Nuggets are quite magical. Only less than 2w words are written on the word limit. Some previous articles wrote almost 30,000 words. The word limit is outrageous. . . 1. The diffing algorithm in React What is virtual Dom: JSX is essentially the syntactic sugar of react.createElement(type,props,...children). The function of react.createElement returns virtual dom. Virtual dom is es

... Patrick
schedule 66 min read
IOS

OC underlying principle 01: -alloc-&-init-&-new- source code analysis

First, let's take a look at an example to analyze the difference between the memory address and pointer address of the three variables; The above outputs areContent, memory address and pointer addressThe output result is: Conclusion: Through the above figure, we can find that three objectsPoint to the same memory space, So theirThe content and memory address are exactly the same, But the pointer address of their object isdifferent It can be found that p1, p2, and p3 are the same, but the address

... Summer
schedule 14 min read
IOS

Swift advanced (1) basic grammar

Introduction to Swift Before learning Swift, let s first understand what Swift is Swift isAppleIn June 2014WWDCThe new programming language released, the Chinese name and LOGO are " " The father of Swift isChris LattnerAnd alsoClangThe author of the compiler,LLVMThe main sponsor of the project Swift version Swift lasted seven years, fromSwift 1.*Update toSwift 5.*, Has undergone many major changes,ABIFinally stabilized API (Application Programming Interface): Application Programming Interface In

... Jameson
schedule 13 min read
IOS

Big talk iOS Layout

Big talk iOS Layout In the development of iOS, we spend most of our time dealing with UI, such as how to layout the UI, how to refresh the UI, and the optimization of complex UI to make our APP more smooth. For UI layout, xcode provides visual layout methods: xib, storyboard, which are very convenient layout methods, what you see is what you get, the threshold is also very low, but it takes up more resources than the code, and in many people In the process of collaborative development, it is ver

... Hannah
schedule 15 min read
IOS

Translation [actual combat]: download tasks using GCD Group and Semaphore

original 1. Brief introduction GCD provides a simple API to create serial and parallel queues to perform background tasks without the developer to manage threads GCD abstracts the allocation of threads for calculation into a dispatch queue. Developers only need to create their own dispatch queue, or they can use the built-in global dispatch queue provided by Apple, which contains several built-inQuality of Service (QoS),includeinteractive, user initiated, utility, and background. GCD will automa

... Kaylee
schedule 11 min read