English
English
A queue is a First-In-First-Out (FIFO) data structure, where elements are added at the tail and removed from the head. A linked list queue is a queue implemented using a linked list, allowing for dynamic size adjustment. It is widely used in many scenarios where FIFO behavior is required.
The linked list queue is implemented using a linked list structure. Each node contains two parts: a data field and a pointer to the next node. The implementation of the queue depends on two pointers, the head and the tail. The head points to the first element, and the tail points to the last element of the queue.
A linked list node consists of two parts: the data field and the pointer to the next node. Below is the PHP implementation of a linked list node:
class Node {
public $data;
public $next;
}The queue consists of two pointers: head and tail. The tail pointer points to the last element in the queue, and the head pointer points to the first element. The length of the queue increases as elements are added. Below is the PHP implementation of a queue:
class Queue {
private $head;
private $tail;
public function __construct() {
$this->head = null;
$this->tail = null;
}
public function isEmpty() {
return $this->head === null;
}
public function enqueue($data) {
$newNode = new Node();
$newNode->data = $data;
$newNode->next = null;
if ($this->isEmpty()) {
$this->head = $this->tail = $newNode;
} else {
$this->tail->next = $newNode;
$this->tail = $newNode;
}
}
public function dequeue() {
if ($this->isEmpty()) {
return null;
}
$data = $this->head->data;
$this->head = $this->head->next;
if ($this->head === null) {
$this->tail = null;
}
return $data;
}
}Linked list queues are commonly used in the following scenarios:
The linked list queue is a common way to implement a FIFO data structure, suitable for many scenarios that require sequential processing. Thanks to the flexibility of linked lists, the queue can dynamically expand to meet the needs of various applications. Its simple and efficient implementation makes the linked list queue an indispensable tool in software design.
