Solve PHP arrays in one minute—how to use quick sort?
PHP中我们了解了那么多关于数组的知识,不知道你们对快速排序有多少了解,我相信很大一部分人会不知道这部分知识点,那么不急本篇文章就是带领大家更深刻的去了解这个内容。
快速排序:
快遠排序(Quicksort)是对冒泡排序的一种改进。通过一-趟排序将要排序的数据分割成独立的两部分,其中-一部分的所有数据都批另外-部分的所有数据都要小,然后再按此方法对这两部分数据分别进行快速排序,整个排序过程可以递归进行,以此达到整个数据变成有序列。
设要排序的数组是.....N-1]首先任意选取一一个数据(通常选用数组的第一个数)作为关键数据,然后将所有比它小的數都放到它前面,所有比它大的数都放到它后面,这个过程称为- -趟快速排序。值得注意的是,快速排序不是一-种稳定的排序算法,也就是说,多个相同的值的相对位置也许会在算法结束时产生变动。
我们以代码为例:
<?php //PHP数组排序:快速排序 $arr = array(1,6,3,4,9,2,7,8); //快速排序 function quick_sort($arr){ //递归出口 $len = count($arr); if($len <= 1) return $arr; //取出某个元素,然后将剩余的数组元素,分散到两个不同的数组中 $left = $right = array(); for($i = 1;$i < $len;$i++){ //第一个元素作为比较元素 //比较:小的放left中,大的放right中 if($arr[$i] < $arr[0]){ $left[] = $arr[$i]; }else{ $right[] = $arr[$i]; } } if($arr[$i] < $arr[0]){ $left[] = $arr[$i]; }else{ $right[] = $arr[$i]; } } //合并三个“数”组. return array_merge($left,(array)$arr[0],$right); } echo '<pre class="brush:php;toolbar:false">'; print_r(quick_sort($arr));
运行结果如下:
//$left和$right数组元素没有排好序:递归点
$1eft = quick_ sort($1eft); $right = quick_ sort($right); .
快速排序的算法是:
1)从数组中选出一 -个元素(通常第一一个), 作为参照对象。。
2)定义两个数组,将目标数组中剩余的元素与参照元素挨个比较:小的放到-一个数组,大的放到另外-一个数组。
3)第二步执行完之后,前后的数组顺序不确定,但是确定了自己的位置。
4)将得到的小数组按照第 1到第3部重复操作(子问题)。
5)回溯最小数组 (一个元素)。
相关学习视频分享:php视频教程
The above is the detailed content of Solve PHP arrays in one minute—how to use quick sort?. For more information, please follow other related articles on the PHP Chinese website!

Hot AI Tools

Undresser.AI Undress
AI-powered app for creating realistic nude photos

AI Clothes Remover
Online AI tool for removing clothes from photos.

Undress AI Tool
Undress images for free

Clothoff.io
AI clothes remover

Video Face Swap
Swap faces in any video effortlessly with our completely free AI face swap tool!

Hot Article

Hot Tools

Notepad++7.3.1
Easy-to-use and free code editor

SublimeText3 Chinese version
Chinese version, very easy to use

Zend Studio 13.0.1
Powerful PHP integrated development environment

Dreamweaver CS6
Visual web development tools

SublimeText3 Mac version
God-level code editing software (SublimeText3)

Hot Topics

PHP 8.4 brings several new features, security improvements, and performance improvements with healthy amounts of feature deprecations and removals. This guide explains how to install PHP 8.4 or upgrade to PHP 8.4 on Ubuntu, Debian, or their derivati

If you are an experienced PHP developer, you might have the feeling that you’ve been there and done that already.You have developed a significant number of applications, debugged millions of lines of code, and tweaked a bunch of scripts to achieve op

Visual Studio Code, also known as VS Code, is a free source code editor — or integrated development environment (IDE) — available for all major operating systems. With a large collection of extensions for many programming languages, VS Code can be c

JWT is an open standard based on JSON, used to securely transmit information between parties, mainly for identity authentication and information exchange. 1. JWT consists of three parts: Header, Payload and Signature. 2. The working principle of JWT includes three steps: generating JWT, verifying JWT and parsing Payload. 3. When using JWT for authentication in PHP, JWT can be generated and verified, and user role and permission information can be included in advanced usage. 4. Common errors include signature verification failure, token expiration, and payload oversized. Debugging skills include using debugging tools and logging. 5. Performance optimization and best practices include using appropriate signature algorithms, setting validity periods reasonably,

This tutorial demonstrates how to efficiently process XML documents using PHP. XML (eXtensible Markup Language) is a versatile text-based markup language designed for both human readability and machine parsing. It's commonly used for data storage an

A string is a sequence of characters, including letters, numbers, and symbols. This tutorial will learn how to calculate the number of vowels in a given string in PHP using different methods. The vowels in English are a, e, i, o, u, and they can be uppercase or lowercase. What is a vowel? Vowels are alphabetic characters that represent a specific pronunciation. There are five vowels in English, including uppercase and lowercase: a, e, i, o, u Example 1 Input: String = "Tutorialspoint" Output: 6 explain The vowels in the string "Tutorialspoint" are u, o, i, a, o, i. There are 6 yuan in total

Static binding (static::) implements late static binding (LSB) in PHP, allowing calling classes to be referenced in static contexts rather than defining classes. 1) The parsing process is performed at runtime, 2) Look up the call class in the inheritance relationship, 3) It may bring performance overhead.

What are the magic methods of PHP? PHP's magic methods include: 1.\_\_construct, used to initialize objects; 2.\_\_destruct, used to clean up resources; 3.\_\_call, handle non-existent method calls; 4.\_\_get, implement dynamic attribute access; 5.\_\_set, implement dynamic attribute settings. These methods are automatically called in certain situations, improving code flexibility and efficiency.
