bucket-priority-queue

Bucket Queue in TypeScript

Overview

BucketQueue is a priority queue implementation ideal for algorithms requiring efficient, priority-based item management, such as Dijkstra's algorithm. It's designed to offer quick enqueue and dequeue operations, particularly when the priority key space is small and comprised of positive integers, a common scenario in many programming puzzles. See Bucket queue on Wikipedia for more.

Benchmarks

Compared to other Heap-based priority queue implementations, BucketQueue can offer a significant performance boost given the right conditions. The following benchmarks - about pop and push operations - were run on a 2021 MacBook Pro with Apple M1 Max chip, Node.js 20.10.0:

BucketQueue x 49,750,443 ops/sec ±0.14% (101 runs sampled)
HeapJS x 12,203,990 ops/sec ±0.18% (99 runs sampled)
HeapDS x 1,094,289 ops/sec ±0.09% (97 runs sampled)
Heap x 4,401,016 ops/sec ±0.10% (98 runs sampled)
MinPriorityQueue x 25,171,646 ops/sec ±0.09% (95 runs sampled)
PriorityQueue x 15,892,132 ops/sec ±0.07% (96 runs sampled)

For more details, see the benchmark source code.

Installation

To install BucketQueue, simply include it in your project dependencies:

npm install bucket-priority-queue

Usage

Here's how you can integrate BucketQueue into your project:

import { MinBucketQueue, MaxBucketQueue } from "bucket-priority-queue";

// Initialize the queue with optional initial items
const queue = new MinBucketQueue<number>([
  [1, 1],
  [2, 2],
  [3, 3],
]);

// Adding items with priority
queue.push(5, 1); // item 5 with priority 1
queue.push(6, 2); // item 6 with priority 2

// Retrieve items with the highest or lowest priority
const lowest = queue.pop(); // returns item with lowest priority

API Reference

MinBucketQueue

MinBucketQueue is a data structure that operates similarly to a priority queue. It organizes elements in a way such that the element with the minimum priority is always at the front.

Methods

• constructor(items?: [T, Priority][]): Initialize a new MinBucketQueue with optional initial items.
• push(item: T, priority: Priority): Adds an item to the queue with an associated priority.
• add(item: T, priority: Priority): Alias for push.
• offer(item: T, priority: Priority): Alias for push.
• pop(): T | undefined: Removes and returns the item with the minimum priority. Returns undefined if the queue is empty.
• poll(): T | undefined: Alias for pop.
• peek(): T | undefined: Returns the item with the minimum priority without removing it from the queue.
• clear(): Removes all items from the queue.
• refill(items: [T, Priority][]): Clears the queue and adds the provided items.
• has(item: T): Checks if the queue contains the specified item.
• contains(item: T): Alias for has.
• toArray(): T[]: Returns an array containing all the items in the queue.
• isEmpty(): boolean: Returns true if the queue is empty, otherwise returns false.
• size: number: Contains the number of items in the queue.
• length: number: Contains the number of items in the queue.

MaxBucketQueue

MaxBucketQueue is a data structure that operates similarly to a priority queue. It organizes elements in a way such that the element with the maximum priority is always at the front.

Methods

• constructor(items?: [T, Priority][]): Initialize a new MaxBucketQueue with optional initial items.
• push(item: T, priority: Priority): Adds an item to the queue with an associated priority.
• add(item: T, priority: Priority): Alias for push.
• offer(item: T, priority: Priority): Alias for push.
• pop(): T | undefined: Removes and returns the item with the maximum priority. Returns undefined if the queue is empty.
• poll(): T | undefined: Alias for pop.
• peek(): T | undefined: Returns the item with the maximum priority without removing it from the queue.
• clear(): Removes all items from the queue.
• refill(items: [T, Priority][]): Clears the queue and adds the provided items.
• has(item: T): Checks if the queue contains the specified item.
• contains(item: T): Alias for has.
• toArray(): T[]: Returns an array containing all the items in the queue.
• isEmpty(): boolean: Returns true if the queue is empty, otherwise returns false.
• size: number: Contains the number of items in the queue.
• length: number: Contains the number of items in the queue.

License

This project is licensed under the MIT License - see the LICENSE file for details.