PHP의 복잡한 데이터 구조 구현에 대한 완벽한 가이드

class HashTable
{
    private $table = [];

    public function put($key, $value)
    {
        $index = hash('sha256', $key);
        $this->table[$index] = $value;
    }

    public function get($key)
    {
        $index = hash('sha256', $key);
        return $this->table[$index] ?? null;
    }
}

$hash = new HashTable();
$hash->put('foo', 'bar');
echo $hash->get('foo'); // 输出: bar

class Node
{
    public $data;
    public $next;
}

class LinkedList
{
    private $head;
    private $tail;

    public function add($data)
    {
        $node = new Node();
        $node->data = $data;
        if ($this->tail !== null) {
            $this->tail->next = $node;
        }
        $this->tail = $node;
        if ($this->head === null) {
            $this->head = $node;
        }
    }

    public function get($index)
    {
        $node = $this->head;
        for ($i = 0; $i < $index; $i++) {
            if ($node === null) {
                return null;
            }
            $node = $node->next;
        }
        return $node->data;
    }
}

$list = new LinkedList();
$list->add(1);
$list->add(2);
$list->add(3);
echo $list->get(1); // 输出: 2

class Stack
{
    private $elements = [];

    public function push($element)
    {
        $this->elements[] = $element;
    }

    public function pop()
    {
        return array_pop($this->elements);
    }

    public function top()
    {
        return end($this->elements);
    }
}

$stack = new Stack();
$stack->push(1);
$stack->push(2);
$stack->push(3);
echo $stack->top(); // 输出: 3

class Node
{
    public $data;
    public $left;
    public $right;
}

class BinarySearchTree
{
    private $root;

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

    private function insertNode($node, $parent)
    {
        if ($node->data < $parent->data) {
            if ($parent->left === null) {
                $parent->left = $node;
            } else {
                $this->insertNode($node, $parent->left);
            }
        } else {
            if ($parent->right === null) {
                $parent->right = $node;
            } else {
                $this->insertNode($node, $parent->right);
            }
        }
    }

    public function find($data)
    {
        return $this->findNode($data, $this->root);
    }

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

$tree = new BinarySearchTree();
$tree->insert(10);
$tree->insert(5);
$tree->insert(15);
$node = $tree->find(15);
echo $node->data; // 输出: 15