@datastructures-js/priority-queue

@datastructures-js/priority-queue

A highly performant priority queue implementation using a Min Heap data structure.

Table of Contents

• Install
• API
  • require
  • import
  • Construction
  • .enqueue(element, priority)
  • .front()
  • .back()
  • .dequeue()
  • .isEmpty()
  • .size()
  • .toArray()
  • .clear()
• Build
• License

Install

npm install --save @datastructures-js/priority-queue

API

require

const PriorityQueue = require('@datastructures-js/priority-queue');

import

import PriorityQueue from '@datastructures-js/priority-queue';

Construction

const priorityQueue = new PriorityQueue();

.enqueue(element, priority)

adds an element with a priority (number) to the queue. The smaller the number, the higher the priority.

params
name	type
element	object
priority	number

runtime
O(log(n))

Example

priorityQueue.enqueue('patient y', 1); // highest priority
priorityQueue.enqueue('patient z', 3);
priorityQueue.enqueue('patient w', 4); // lowest priority
priorityQueue.enqueue('patient x', 2);

.front()

returns the element with highest priority in the queue.

return	description
object	object literal with "priority" and "element" props

runtime
O(1)

Example

console.log(priorityQueue.front()); // { priority: 1, element: 'patient y' }

.back()

returns an element with lowest priority in the queue. If multiple elements exist at the lowest priority, the one that was inserted first will be returned.

return	description
object	object literal with "priority" and "element" props

runtime
O(1)

Example

priorityQueue.enqueue('patient m', 4); // lowest priority
priorityQueue.enqueue('patient c', 4); // lowest priority
console.log(priorityQueue.back()); // { priority: 4, element: 'patient w' }

.dequeue()

removes and returns the element with highest priority in the queue.

return	description
object	object literal with "priority" and "element" props

runtime
O(log(n))

Example

console.log(priorityQueue.dequeue()); // { priority: 1, element: 'patient y' }
console.log(priorityQueue.front()); // { priority: 2, element: 'patient x' }

.isEmpty()

checks if the queue is empty.

return
boolean

runtime
O(1)

Example

console.log(priorityQueue.isEmpty()); // false

.size()

returns the number of elements in the queue.

return
number

runtime
O(1)

Example

console.log(priorityQueue.size()); // 5

.toArray()

returns a sorted array of elements by their priorities from highest to lowest.

return	description
array	an array of object literals with "priority" & "element" props

runtime
O(n*log(n))

Example

console.log(priorityQueue.toArray());
/*
[
  { priority: 2, element: 'patient x' },
  { priority: 3, element: 'patient z' },
  { priority: 4, element: 'patient c' },
  { priority: 4, element: 'patient w' },
  { priority: 4, element: 'patient m' }
]
*/

.clear()

clears all elements in the queue.

runtime
O(1)

Example

priorityQueue.clear();
console.log(priorityQueue.size()); // 0
console.log(priorityQueue.front()); // null
console.log(priorityQueue.dequeue()); // null

Build

grunt build

License

The MIT License. Full License is here