


PHP implementation of binary tree traversal algorithm demonstration
Jun 17, 2017 am 10:46 AMThis article mainly introduces the binary tree traversal algorithm implemented by PHP, and analyzes PHP's commonly used pre-order, mid-order and post-order traversal algorithm implementation techniques for binary trees in the form of specific examples. Friends in need can refer to the following
The example in this article describes the binary tree traversal algorithm implemented in PHP. Share it with everyone for your reference, the details are as follows:
Today I used php to implement binary tree traversal
The created binary tree is as shown below
php code is as follows:
<?php class Node { public $value; public $child_left; public $child_right; } final class Ergodic { //前序遍歷:先訪問(wèn)根節(jié)點(diǎn),再遍歷左子樹(shù),最后遍歷右子樹(shù);并且在遍歷左右子樹(shù)時(shí),仍需先遍歷根節(jié)點(diǎn),然后訪問(wèn)左子樹(shù),最后遍歷右子樹(shù) public static function preOrder($root){ $stack = array(); array_push($stack, $root); while(!empty($stack)){ $center_node = array_pop($stack); echo $center_node->value . ' '; //先把右子樹(shù)節(jié)點(diǎn)入棧,以確保左子樹(shù)節(jié)點(diǎn)先出棧 if($center_node->child_right != null) array_push($stack, $center_node->child_right); if($center_node->child_left != null) array_push($stack, $center_node->child_left); } } //中序遍歷:先遍歷左子樹(shù)、然后訪問(wèn)根節(jié)點(diǎn),最后遍歷右子樹(shù);并且在遍歷左右子樹(shù)的時(shí)候。仍然是先遍歷左子樹(shù),然后訪問(wèn)根節(jié)點(diǎn),最后遍歷右子樹(shù) public static function midOrder($root){ $stack = array(); $center_node = $root; while (!empty($stack) || $center_node != null) { while ($center_node != null) { array_push($stack, $center_node); $center_node = $center_node->child_left; } $center_node = array_pop($stack); echo $center_node->value . ' '; $center_node = $center_node->child_right; } } //后序遍歷:先遍歷左子樹(shù),然后遍歷右子樹(shù),最后訪問(wèn)根節(jié)點(diǎn);同樣,在遍歷左右子樹(shù)的時(shí)候同樣要先遍歷左子樹(shù),然后遍歷右子樹(shù),最后訪問(wèn)根節(jié)點(diǎn) public static function endOrder($root){ $push_stack = array(); $visit_stack = array(); array_push($push_stack, $root); while (!empty($push_stack)) { $center_node = array_pop($push_stack); array_push($visit_stack, $center_node); //左子樹(shù)節(jié)點(diǎn)先入$pushstack的棧,確保在$visitstack中先出棧 if ($center_node->child_left != null) array_push($push_stack, $center_node->child_left); if ($center_node->child_right != null) array_push($push_stack, $center_node->child_right); } while (!empty($visit_stack)) { $center_node = array_pop($visit_stack); echo $center_node->value . ' '; } } } //創(chuàng)建二叉樹(shù) $a = new Node(); $b = new Node(); $c = new Node(); $d = new Node(); $e = new Node(); $f = new Node(); $g = new Node(); $h = new Node(); $i = new Node(); $a->value = 'A'; $b->value = 'B'; $c->value = 'C'; $d->value = 'D'; $e->value = 'E'; $f->value = 'F'; $g->value = 'G'; $h->value = 'H'; $i->value = 'I'; $a->child_left = $b; $a->child_right = $c; $b->child_left = $d; $b->child_right = $g; $c->child_left = $e; $c->child_right = $f; $d->child_left = $h; $d->child_right = $i; //前序遍歷 Ergodic::preOrder($a); //結(jié)果是:A B D H I G C E F echo '<br/>'; //中序遍歷 Ergodic::midOrder($a); //結(jié)果是: H D I B G A E C F echo '<br/>'; //后序遍歷 Ergodic::endOrder($a); //結(jié)果是: H I D G B E F C A
The above is the detailed content of PHP implementation of binary tree traversal algorithm demonstration. For more information, please follow other related articles on the PHP Chinese website!

Hot AI Tools

Undress AI Tool
Undress images for free

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

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

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

The key to setting up PHP is to clarify the installation method, configure php.ini, connect to the web server and enable necessary extensions. 1. Install PHP: Use apt for Linux, Homebrew for Mac, and XAMPP recommended for Windows; 2. Configure php.ini: Adjust error reports, upload restrictions, etc. and restart the server; 3. Use web server: Apache uses mod_php, Nginx uses PHP-FPM; 4. Install commonly used extensions: such as mysqli, json, mbstring, etc. to support full functions.

ToinstallPHPquickly,useXAMPPonWindowsorHomebrewonmacOS.1.OnWindows,downloadandinstallXAMPP,selectcomponents,startApache,andplacefilesinhtdocs.2.Alternatively,manuallyinstallPHPfromphp.netandsetupaserverlikeApache.3.OnmacOS,installHomebrew,thenrun'bre

There are three common methods for PHP comment code: 1. Use // or # to block one line of code, and it is recommended to use //; 2. Use /.../ to wrap code blocks with multiple lines, which cannot be nested but can be crossed; 3. Combination skills comments such as using /if(){}/ to control logic blocks, or to improve efficiency with editor shortcut keys, you should pay attention to closing symbols and avoid nesting when using them.

Comments cannot be careless because they want to explain the reasons for the existence of the code rather than the functions, such as compatibility with old interfaces or third-party restrictions, otherwise people who read the code can only rely on guessing. The areas that must be commented include complex conditional judgments, special error handling logic, and temporary bypass restrictions. A more practical way to write comments is to select single-line comments or block comments based on the scene. Use document block comments to explain parameters and return values at the beginning of functions, classes, and files, and keep comments updated. For complex logic, you can add a line to the previous one to summarize the overall intention. At the same time, do not use comments to seal code, but use version control tools.

The key to writing good comments is to explain "why" rather than just "what was done" to improve the readability of the code. 1. Comments should explain logical reasons, such as considerations behind value selection or processing; 2. Use paragraph annotations for complex logic to summarize the overall idea of functions or algorithms; 3. Regularly maintain comments to ensure consistency with the code, avoid misleading, and delete outdated content if necessary; 4. Synchronously check comments when reviewing the code, and record public logic through documents to reduce the burden of code comments.

The key to writing PHP comments is to clarify the purpose and specifications. Comments should explain "why" rather than "what was done", avoiding redundancy or too simplicity. 1. Use a unified format, such as docblock (/*/) for class and method descriptions to improve readability and tool compatibility; 2. Emphasize the reasons behind the logic, such as why JS jumps need to be output manually; 3. Add an overview description before complex code, describe the process in steps, and help understand the overall idea; 4. Use TODO and FIXME rationally to mark to-do items and problems to facilitate subsequent tracking and collaboration. Good annotations can reduce communication costs and improve code maintenance efficiency.

TolearnPHPeffectively,startbysettingupalocalserverenvironmentusingtoolslikeXAMPPandacodeeditorlikeVSCode.1)InstallXAMPPforApache,MySQL,andPHP.2)Useacodeeditorforsyntaxsupport.3)TestyoursetupwithasimplePHPfile.Next,learnPHPbasicsincludingvariables,ech

PHPblockcommentsareusefulforwritingmulti-lineexplanations,temporarilydisablingcode,andgeneratingdocumentation.Theyshouldnotbenestedorleftunclosed.BlockcommentshelpindocumentingfunctionswithPHPDoc,whichtoolslikePhpStormuseforauto-completionanderrorche
