A PriorityQueue is a type of queue where each element has a priority. The
element with the highest priority is always at the front of the queue. This
type of queue is built using a max heap.
Requirements:
To use PriorityQueue, you need PHP 7 for the extension and compatibility
polyfill.
Installation:
The simplest way to install the data structure is by using the PECL extension.
Run the following command:
pecl install ds
Syntax:
To use a function from PriorityQueue, you can call it like this:
public Ds\PriorityQueue::functionName()
Example:
Here's an example of how to use the
`Ds\PriorityQueue::count()`
function in PHP:
<?php
// Create a new PriorityQueue
$pq = new \Ds\PriorityQueue();
// Add elements with priorities
$pq->push("One", 1);
$pq->push("Two", 2);
$pq->push("Three", 3);
// Count the number of elements
echo $pq->count();
?>
Output:
3
In this example, we created a priority queue, added three elements with
different priorities, and then counted how many elements are in the queue. The
output is 3.
Complete list of PHP Ds\PriorityQueue Functions:
| Ds\PriorityQueue Functions | Description |
|---|---|
| allocate(size) | Allocate memory for the priority queue to hold a specific number of elements (`size`). This pre-allocates space to potentially avoid performance overhead during insertions or removals. |
| capacity() | Return the current maximum number of elements the priority queue can hold without needing reallocation. |
| clear() | Remove all elements from the priority queue. |
| copy() | Create a new priority queue that is a shallow copy of the original queue. Changes to the original queue will not be reflected in the copy, and vice versa. |
| count() | Return the number of elements currently in the priority queue. |
| isEmpty() | Check whether the priority queue is empty (contains no elements). |
| peek() | Return the element with the highest priority (smallest value by default) from the priority queue without removing it. If the queue is empty, it may return an error or null value. |
| pop() | Remove and return the element with the highest priority (smallest value by default) from the priority queue. If the queue is empty, it may return an error or null value. |
| push(value, priority) | Add a new element to the priority queue. The element will be inserted according to its priority (higher priority values will be placed at the front). You can optionally specify a priority value, otherwise a default priority will be used. |
| toArray() | Convert the priority queue to a regular PHP array. The order of elements in the resulting array may not reflect the priority order in the queue. |