Build advanced search tree data structures with PHP

Building advanced search trees using PHP involves creating node classes (Node) and search tree classes (SearchTree), and implementing methods for inserting, finding, and deleting elements. The elements are stored in a binary tree in logarithmic time complexity, with each node containing a value and links to its left and right subtrees. In practice, you can create a search tree and insert elements, find specific values, or even delete elements from the tree.

Using PHP to build advanced search tree data structures

The search tree is an efficient data structure that allows logarithmic Find, insert and delete elements within time complexity. This article will guide you through building an advanced search tree using PHP.

1. Create a node class

First, create a class named Node to represent the nodes in the tree:

class Node {
    public $value;
    public $left;
    public $right;

    public function __construct($value) {
        $this->value = $value;
        $this->left = null;
        $this->right = null;
    }
}

2. Create a search tree class

Next, create a class named SearchTree to represent the search tree itself:

class SearchTree {
    private $root;

    public function __construct() {
        $this->root = null;
    }

    // 其他方法（见下文）
}

3. Insert element

To insert a new element, you can use the following method:

public function insert($value) {
    if ($this->root === null) {
        $this->root = new Node($value);
    } else {
        $this->_insert($value, $this->root);
    }
}

private function _insert($value, $node) {
    if ($value < $node->value) {
        if ($node->left === null) {
            $node->left = new Node($value);
        } else {
            $this->_insert($value, $node->left);
        }
    } else {
        if ($node->right === null) {
            $node->right = new Node($value);
        } else {
            $this->_insert($value, $node->right);
        }
    }
}

4. Find the element

To To find an element, you can use the following method:

public function find($value) {
    if ($this->root === null) {
        return null;
    } else {
        return $this->_find($value, $this->root);
    }
}

private function _find($value, $node) {
    if ($value === $node->value) {
        return $node;
    } elseif ($value < $node->value) {
        if ($node->left === null) {
            return null;
        } else {
            return $this->_find($value, $node->left);
        }
    } else {
        if ($node->right === null) {
            return null;
        } else {
            return $this->_find($value, $node->right);
        }
    }
}

5. Delete element

To delete an element, you can use the following method (this is a recursive process, specifically Implementation omitted):

public function delete($value) {
    if ($this->root === null) {
        return;
    } else {
        $this->root = $this->_delete($value, $this->root);
    }
}

private function _delete($value, $node) {
    // ...
}

Practical case

Let us create a search tree and insert some elements:

$tree = new SearchTree();
$tree->insert(10);
$tree->insert(5);
$tree->insert(15);
$tree->insert(7);
$tree->insert(12);
$tree->insert(20);

Then, we can find an element :

$foundNode = $tree->find(12);
if ($foundNode !== null) {
    echo "Found the node with value 12." . PHP_EOL;
}

Finally, we can delete an element:

$tree->delete(12);

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