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1. Problem Description: Farmer John has n cows numbered 1... N. He milks his cows every day. The social structure of dairy cows is very complex, and its structure has two key characteristics. First of all, there are M cows with distinct status levels. According to the rule that the higher the status, the earlier the milking, the relative milki ...

01. Add, delete and modify insert record SQL1 insert record (I) Now there are two users' response records, as follows: User 1001 began to answer test paper 9001 at 10:11:12 p.m. on September 1, 2021, and submitted it 50 minutes later, with 90 points;User 1002 began to answer test paper 9002 at 7:1:2 a.m. on September 4, 2021, and quit the p ...

Types of animation Android animation can be roughly divided into the following three types: Draw animation View animation Property animation Generally speaking, attribute animation is the preferred method because it is more flexible and provides more functions. View animation and frame by frame animation seem to withdraw from the stage of histo ...

The arrow function is used in this article. If you don't know, you can check it 👇 ES6 study noteshttps://blog.csdn.net/TeAmo__/article/details/123053529?spm=1001.2014.3001.5501 catalogue forEach traversal filter filtering Find find findIndex find subscript map mapping reduce accumulation Some some every all Sort sort forEach tr ...

Encapsulation of native ajax requests The native ajax request is divided into four steps: 1. Create request object Determine browser compatibility issues ie browser: window ActiveXObject Common browser: window XMLHttpRequest if (window.XMLHttpRequest) { var xhr = new XMLHttpRequest(); } else if (window.ActiveXObject) { ...

Purpose: Read cache to reduce server pressure and improve performance;Temporary data, such as validity verification code; 1,JSR107 (1) java caching defines five core interfaces Cache provider: create, configure, obtain, manage and control the cache manager. An application can access multiple cache providers at runtime;chchemanager: create, ...

User information table: user_profile Device ID (device_id) gender age School (university) active_days_within_30 field Post quantity field (question_cnt) Answer quantity field (answer_cnt) iddevice_idgenderageuniversitygpaactive_days_within_30question_cntanswer_cnt12138male21Peking University3.4721223214maleNULLFudan University4155253654 ...

Blocking queue Blocking queues are often used in producer consumer scenarios. In java8, JUC provides seven blocking queues. Class nameeffectArrayBlockingQueueThe bounded blocking queue implemented by the array sorts the elements according to the first in first out (FIFO) principle.LinkedBlockingQueueA bounded blocking queue implemented by a l ...

preface this topic is an unavoidable difficulty in study, work and interview. Let's start with a topic: var name = "Xiao Hong"; function a() { var name = "Xiaobai"; console.log(this.name); } function d(i) { return i(); } var b = { name: "Xiao Huang", detail: function() { console.log(this.name); }, show: fu ...

ArrayList underlying source code conclusion ArrayList maintains an array of object type elementdata (transient Object[] elementData;)When creating an ArrayList object, if a parameterless constructor is used, the initial elementData capacity is 0. If it is added for the first time, the expanded elementData is 10. If it needs to be expanded aga ...