PHP Class&Object -- 解析PHP实现二叉树

yipeiwu_com6年前PHP代码库
二叉树及其变体是数据结构家族里的重要组成部分。最为链表的一种变体,二叉树最适合处理需要一特定次序快速组织和检索的数据。
复制代码 代码如下:

<?php
// Define a class to implement a binary tree
class Binary_Tree_Node {
    // Define the variable to hold our data:
    public $data;
    // And a variable to hold the left and right objects:
    public $left;
    public $right;

    // A constructor method that allows for data to be passed in
    public function __construct($d = NULL) {
        $this->data = $d;
    }

    // Traverse the tree, left to right, in pre-order, returning an array
    // Preorder means that each node's value preceeds its children.
    public function traversePreorder() {
        // Prep some variables.
        $l = array();
        $r = array();
        // Read in the left and right children appropriately traversed:
        if ($this->left) { $l = $this->left->traversePreorder(); }
        if ($this->right) { $r = $this->right->traversePreorder(); }

        // Return a merged array of the current value, left, and right:
        return array_merge(array($this->data), $l, $r);
    }
    // Traverse the tree, left to right, in postorder, returning an array
    // Postorder means that each node's value follows its children.
    public function traversePostorder() {
        // Prep some variables.
        $l = array();
        $r = array();
        // Read in the left and right children appropriately traversed:
        if ($this->left) { $l = $this->left->traversePostorder(); }
        if ($this->right) { $r = $this->right->traversePostorder(); }

        // Return a merged array of the current value, left, and right:
        return array_merge($l, $r, array($this->data));
    }
    // Traverse the tree, left to right, in-order, returning an array.
    // In-order means that values are ordered as left children, then the
    //  node value, then the right children.
    public function traverseInorder() {
        // Prep some variables.
        $l = array();
        $r = array();
        // Read in the left and right children appropriately traversed:
        if ($this->left) { $l = $this->left->traverseInorder(); }
        if ($this->right) { $r = $this->right->traverseInorder(); }

        // Return a merged array of the current value, left, and right:
        return array_merge($l, array($this->data), $r);
    }
}
// Let's create a binary tree that will equal the following:    3
//                                                             / /     
//                                                            h   9     
//                                                               / /    
// Create the tree:                                             6   a   
$tree = new Binary_Tree_Node(3);
$tree->left = new Binary_Tree_Node('h');
$tree->right = new Binary_Tree_Node(9);
$tree->right->left = new Binary_Tree_Node(6);
$tree->right->right = new Binary_Tree_Node('a');
// Now traverse this tree in all possible orders and display the results:
// Pre-order: 3, h, 9, 6, a
echo '<p>', implode(', ', $tree->traversePreorder()), '</p>';
// Post-order: h, 9, 6, a, 3
echo '<p>', implode(', ', $tree->traversePostorder()), '</p>';
// In-order: h, 3, 6, 9, a
echo '<p>', implode(', ', $tree->traverseInorder()), '</p>';
?>

相关文章

ThinkPHP5 验证器的具体使用

ThinkPHP5 验证器的具体使用

前言: 我们在做API开发的时候,我们会接受客户端传来的参数,大家都知道这个参数是不可信的,我们后端开发人员必须对这个参数进行验证。我在之前的开发中只是知道tp5的验证器,并不知道他的用...

PHP实现抓取HTTPS内容

PHP实现抓取HTTPS内容

最近在研究Hacker News API时遇到一个HTTPS问题。因为所有的Hacker News API都是通过加密的HTTPS协议访问的,跟普通的HTTP协议不同,当使用PHP里的函...

php实现的rc4加密解密类定义与用法示例

本文实例讲述了php实现的rc4加密解密类。分享给大家供大家参考,具体如下: class.rc4crypt.php文件: <?php /* * By julying...

php fputcsv命令 写csv文件遇到的小问题(多维数组连接符)

php fputcsv命令 写csv文件遇到的小问题(多维数组连接符)

命令: fputcsv() 命令格式:int fputcsv ( resource handle [, array fields [, string delimiter [, strin...

PHP里的$_GET数组介绍

在开发过程中,GET和POST无处不在。$_GET 变量是一个数组,内容是由 HTTP GET 方法发送的变量名称和值。 $_GET 变量用于收集来自 method="get" 的表单中...