PHP simple selection sorting algorithm learning sharing
This article mainly introduces the PHP Simple Selection Sort algorithm in detail. It has certain reference value. Interested friends can refer to it. I hope it can help everyone.
The example in this article shares the specific code of simple selection sorting in PHP for your reference. The specific content is as follows
Basic idea:
Pass n - Comparison between i keywords, select the record with the smallest keyword from n - i + 1 records, and exchange it with the i (1 <= i <= n) record, executing n-1 times Finally, the sorting of the record sequence is completed.
Algorithm implementation:
<?php
//简单选择排序
//交换函数
function swap(array &$arr,$a,$b){
$temp = $arr[$a];
$arr[$a] = $arr[$b];
$arr[$b] = $temp;
}
//简单选择排序算法
function SelectSort(array &$arr){
$count = count($arr);
for($i = 0;$i < $count - 1;$i ++){
//记录第$i个元素后的所有元素最小值下标
$min = $i;
for($j = $i + 1;$j < $count;$j ++){
if($arr[$j] < $arr[$min]){
$min = $j;
}
}
if($min != $i){
swap($arr,$min,$i);
}
}
}
$arr = array(9,1,5,8,3,7,4,6,2);
SelectSort($arr);
var_dump($arr);Complexity analysis:
In simple selection During the sorting process, the number of records required to be moved is relatively small. In the best case, that is, the initial state of the records to be sorted is already in positive order, and there is no need to move the records.
In the worst case, that is, the initial state of the records to be sorted is that the first record is the largest, and subsequent records are arranged in ascending order, then the number of records that need to be moved is at most 3 (n-1). The number of comparisons required during simple selection sorting has nothing to do with the arrangement of the record sequence to be sorted in the initial state. When i=1, n-1 comparisons are required; when i=2, n-2 comparisons are required; and so on, the total number of comparisons required is (n-1)+(n-2)+ ...+2+1=n(n-1)/2, that is, the time complexity of the comparison operation is O(n^2), and the time complexity of the move operation is O(n).
Simple selection sort is unstable sorting.
Related recommendations:
Detailed explanation of direct selection sorting in the PHP sorting algorithm series
Detailed explanation of bucket sorting in the PHP sorting algorithm series_php skills
Detailed analysis of the method of implementing Hill sorting algorithm in PHP
The above is the detailed content of PHP simple selection sorting algorithm learning sharing. 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 Installation and Upgrade guide for Ubuntu and Debian
Dec 24, 2024 pm 04:42 PM
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
7 PHP Functions I Regret I Didn't Know Before
Nov 13, 2024 am 09:42 AM
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
How To Set Up Visual Studio Code (VS Code) for PHP Development
Dec 20, 2024 am 11:31 AM
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
Explain JSON Web Tokens (JWT) and their use case in PHP APIs.
Apr 05, 2025 am 12:04 AM
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,
PHP Program to Count Vowels in a String
Feb 07, 2025 pm 12:12 PM
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
How do you parse and process HTML/XML in PHP?
Feb 07, 2025 am 11:57 AM
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
Explain late static binding in PHP (static::).
Apr 03, 2025 am 12:04 AM
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 PHP magic methods (__construct, __destruct, __call, __get, __set, etc.) and provide use cases?
Apr 03, 2025 am 12:03 AM
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.
