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6f6f7f749b
An efficient JS implementation of a binary heap on top of an array with worst-case O(log n) runtime for all operations, including arbitrary item removal (unlike O(n) for most binary heap array implementations). PR-URL: https://github.com/nodejs/node/pull/20555 Fixes: https://github.com/nodejs/node/issues/16105 Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl> Reviewed-By: Jeremiah Senkpiel <fishrock123@rocketmail.com> Reviewed-By: Matteo Collina <matteo.collina@gmail.com> Reviewed-By: James M Snell <jasnell@gmail.com> Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
98 lines
2.3 KiB
JavaScript
98 lines
2.3 KiB
JavaScript
// Flags: --expose-internals
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'use strict';
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require('../common');
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const assert = require('assert');
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const PriorityQueue = require('internal/priority_queue');
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{
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// Checks that the queue is fundamentally correct.
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const queue = new PriorityQueue();
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for (let i = 15; i > 0; i--)
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queue.insert(i);
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for (let i = 1; i < 16; i++) {
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assert.strictEqual(queue.peek(), i);
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assert.strictEqual(queue.shift(), i);
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}
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assert.strictEqual(queue.shift(), undefined);
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// Reverse the order.
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for (let i = 1; i < 16; i++)
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queue.insert(i);
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for (let i = 1; i < 16; i++) {
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assert.strictEqual(queue.shift(), i);
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}
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assert.strictEqual(queue.shift(), undefined);
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}
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{
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// Checks that the queue is capable of resizing and fitting more elements.
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const queue = new PriorityQueue();
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for (let i = 2048; i > 0; i--)
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queue.insert(i);
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for (let i = 1; i < 2049; i++) {
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assert.strictEqual(queue.shift(), i);
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}
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assert.strictEqual(queue.shift(), undefined);
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}
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{
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// Checks that remove works as expected.
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const queue = new PriorityQueue();
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for (let i = 16; i > 0; i--)
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queue.insert(i);
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const removed = [5, 10, 15];
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for (const id of removed)
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assert(queue.remove(id));
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assert(!queue.remove(100));
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assert(!queue.remove(-100));
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for (let i = 1; i < 17; i++) {
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if (removed.indexOf(i) < 0)
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assert.strictEqual(queue.shift(), i);
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}
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assert.strictEqual(queue.shift(), undefined);
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}
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{
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// Make a max heap with a custom sort function.
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const queue = new PriorityQueue((a, b) => b - a);
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for (let i = 1; i < 17; i++)
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queue.insert(i);
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for (let i = 16; i > 0; i--) {
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assert.strictEqual(queue.shift(), i);
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}
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assert.strictEqual(queue.shift(), undefined);
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}
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{
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// Make a min heap that accepts objects as values, which necessitates
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// a custom sorting function. In addition, add a setPosition function
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// as 2nd param which provides a reference to the node in the heap
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// and allows speedy deletions.
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const queue = new PriorityQueue((a, b) => {
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return a.value - b.value;
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}, (node, pos) => (node.position = pos));
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for (let i = 1; i < 17; i++)
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queue.insert({ value: i, position: null });
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for (let i = 1; i < 17; i++) {
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assert.strictEqual(queue.peek().value, i);
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queue.removeAt(queue.peek().position);
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}
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assert.strictEqual(queue.peek(), undefined);
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}
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