QA Official

winnowing algorithm-extracting document fingerprint features 2019-04-05
The simple explanation of winnowing algorithm is: based on the Hash code of k-gram, the Hash code of partial gram is extracted by minimum rules as the fingerprint of document features, and the position of gram is recorded.The source code and steps are as follows: (1) Mark the document with characters, such as " asdf", and change it to [ (0, " a"), (1, " s"), (2, " d"), (3,

MD5 Information message digest algorithms 2019-04-04
MD5 is Message-Digest Algorithm 5 (Information message digest algorithms 5), which is one of the hashing algorithms widely used by computers.Developed by MD2, MD3 and MD4, it was born in the early 1990s.Used to ensure complete and consistent information transmission.Although it has been cracked, it still has good security and can be used free of charge, so it is still widely used in digital signature, file integrity verification, password encryption

PCA Face Recognition Personal Understanding and Steps 2019-04-04
PCA Face Recognition Personal Understanding and Steps Preface PCA, principal component analysis, is a method of data dimensionality reduction, and is also an ancient and classic face recognition algorithm.Understanding the principle and steps of PCA algorithm is very helpful to our thinking.Although PCA is relatively simple among many face recognition methods, it is not easy to clearly understand the detailed steps and details of PCA face recognition, especially for beginners.

Spring AOP Understanding and Application Scenarios 2019-04-04
AOP related concepts AOP is short for Aspect Oriented Programming, Aspect Oriented Programming.AOP is suitable for applications with crosscutting logic, such as performance monitoring, access control, transaction management, caching, object pool management, and logging.AOP extracts these codes scattered in each business logic into an independent module through horizontal cutting.The key to AOP implementation lies in the AOP proxies automatically created by the AOP framework. AOP proxies can be divided into two categories: static proxies and dynamic proxies, where static proxies refer to the use of commands provided by the AOP framework for compilation, so that AOP proxy classes can be generated at the compilation stage, which is also called compile-time enhancement.

Spring Framework Benefits and IOC Personal Summary 2019-04-04
spring是一个一站式轻量级开源框架,Spring提供了JavaEE各层的解决方案,表现层:Spring MVC,持久层:JdbcTempl

Spring Framework Interview Summary 2019-04-04
1. What is Spring? A: spring's core is a lightweight Container, which implements IoC(Inversion)Of Control) container and non-invasive framework, and provide the implementation of AOP(Aspect-oriented Programming), provide support for Persistence and Transcation;It provides the implementation of MVC Web framework and provides consistent model encapsulation for some common enterprise service API. It is an all-round application framework. In addition, Spring also provides a scheme to integrate with various existing frameworks (Structs, JSF, hibernate, Ibatis, Webwork, etc.

Spring Principle (2) ApplicationContext of IoC Container Initialization Process 2019-04-04
The previous article has already introduced the initialization process of BeanFactory, and this article introduces the initialization of ApplicationContext.There are many implementations of ApplicationContext. here, take the common filesystemxmlApplicationContext as an example to illustrate the initialization process of applicationcontext. start ApplicationContextThe following code initializes an IoC container, filesystemxmlapplicationcext, which can get the configured bean object through getBean. FileSystemXmlApplicationContext ctx = new FileSystemXmlApplicationContext("D:/workspace/demo_spring/src/main/resources/applicationContext.xml"); System.out.println(ctx.getBean("userService")); Let's continue to look at what exactly

Spring's IOC Event Use 2019-04-04
Spring's event mechanism uses Observer pattern Observer pattern defines a one-to-many dependency between objects, so that when an object changes state, all its dependencies will be notified and automatically updated.Themes and observers define a one-to-many relationship.Observers depend on the topic and will be notified whenever the status of the topic changes.Depending on the style of the notification, the observer may be updated with the new value.The power of loose coupling.

Spring4.x Learning Notes-Spring Concept, IOC Concept and Basic Usage 2019-04-04
1. Spring Framework Related Concepts Open Source Lightweight Framework Spring framework mainly involves two partsAOP: Aspect Oriented Programming (Optimization of Code Extension)IOC: Inversion of Control (Change in Object Creation Method) Spring is a one-stop framework, providing technical support in javaee three layers.Web layer (presentation layer): springMVCServive Layer (Business Logic Layer): IOC of springDao Layer (Data Access Layer): spring's jdbcTemplate 2. IOC Operation Basis of spring (Configuration File Method) 1, the

[JZOJ4816]label 2019-04-04
general idea of topic A tree of size nn, each node can be given an integer weight within [1,m][1,m].It is required that the absolute value of the weight difference between adjacent nodes is not less than kk. Find the number of schemes and modulo 109+710 9+7. TT group data for one test point. 1≤T≤10,1≤n,k≤102,m≤1091\le T\le 10,1\le n,k\le 10^2,m\le10^9 topic analysis An obvious method is to make fx,yf_{x,y} represent the number of schemes where the value of point xx takes yy.