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Commit 874f3eb

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✨ feat (heap): Add Heap implementation (PriorityQueue) (amejiarosario#51)
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‎src/data-structures/trees/heap.js

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class Heap {
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constructor(comparator = (a, b) => a - b) {
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this.array = [];
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this.comparator = (i1, i2) => comparator(this.array[i1], this.array[i2]);
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}
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add(value) {
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this.array.push(value);
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this.bubbleUp();
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}
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peek() {
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return this.array[0];
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}
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remove() {
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this.swap(0, this.size() - 1);
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const value = this.array.pop();
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this.bubbleDown();
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return value;
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}
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size() {
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return this.array.length;
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}
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bubbleUp() {
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let index = this.size() - 1;
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const parent = (i) => Math.ceil(i / 2 - 1);
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while (parent(index) >= 0 && this.comparator(parent(index), index) > 0) {
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this.swap(parent(index), index);
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index = parent(index);
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}
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}
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bubbleDown() {
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let index = 0;
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const left = (i) => 2 * i + 1;
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const right = (i) => 2 * i + 2;
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const getTopChild = (i) => (right(i) < this.size()
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&& this.comparator(left(i), right(i)) > 0 ? right(i) : left(i));
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while (left(index) < this.size() && this.comparator(index, getTopChild(index)) > 0) {
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const next = getTopChild(index);
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this.swap(index, next);
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index = next;
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}
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}
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swap(i1, i2) {
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[this.array[i1], this.array[i2]] = [this.array[i2], this.array[i1]];
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}
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}
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module.exports = Heap;

‎src/data-structures/trees/heap.spec.js

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const Heap = require('./heap');
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describe('Min-Heap (Priority Queue)', () => {
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let heap;
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beforeEach(() => {
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heap = new Heap();
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});
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describe('#contructor', () => {
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it('should initialize', () => {
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expect(heap).not.toBe(undefined);
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});
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});
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describe('#add', () => {
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it('should add an element', () => {
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expect(heap.add(1)).toBe(undefined);
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expect(heap.array).toEqual([1]);
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expect(heap.size()).toBe(1);
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});
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it('should keep things in order', () => {
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heap.add(3);
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expect(heap.array[0]).toEqual(3);
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heap.add(2);
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expect(heap.array[0]).toEqual(2);
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heap.add(1);
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expect(heap.array[0]).toEqual(1);
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expect(heap.size()).toEqual(3);
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});
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});
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describe('#remove', () => {
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it('should work', () => {
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heap.add(1);
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heap.add(0);
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expect(heap.remove()).toBe(0);
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expect(heap.size()).toBe(1);
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expect(heap.array).toEqual([1]);
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});
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});
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describe('when has elements', () => {
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beforeEach(() => {
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heap.add(1);
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heap.add(2);
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heap.add(3);
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heap.add(0);
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});
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describe('#peek', () => {
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it('should get min', () => {
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expect(heap.peek()).toEqual(0);
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});
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});
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describe('#remove', () => {
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it('should get min', () => {
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expect(heap.remove()).toEqual(0);
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expect(heap.remove()).toEqual(1);
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expect(heap.remove()).toEqual(2);
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expect(heap.remove()).toEqual(3);
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expect(heap.size()).toBe(0);
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});
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});
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});
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});
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describe('Max-Heap (Priority Queue)', () => {
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let heap;
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beforeEach(() => {
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heap = new Heap((a, b) => b - a);
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});
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describe('#contructor', () => {
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it('should initialize', () => {
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expect(heap).not.toBe(undefined);
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});
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});
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describe('#add', () => {
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it('should add an element', () => {
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expect(heap.add(1)).toBe(undefined);
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expect(heap.array).toEqual([1]);
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expect(heap.size()).toBe(1);
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});
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it('should keep things in order', () => {
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heap.add(1);
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expect(heap.array[0]).toEqual(1);
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heap.add(2);
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expect(heap.array[0]).toEqual(2);
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heap.add(3);
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expect(heap.array[0]).toEqual(3);
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expect(heap.size()).toEqual(3);
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});
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});
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describe('#remove', () => {
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it('should work', () => {
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heap.add(1);
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heap.add(0);
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expect(heap.remove()).toBe(1);
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expect(heap.size()).toBe(1);
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expect(heap.array).toEqual([0]);
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});
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it('should work with duplicates', () => {
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heap.add(3);
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heap.add(2);
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heap.add(3);
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heap.add(1);
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heap.add(2);
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heap.add(4);
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heap.add(5);
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heap.add(5);
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heap.add(6);
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expect(heap.remove()).toEqual(6);
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expect(heap.remove()).toEqual(5);
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expect(heap.remove()).toEqual(5);
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expect(heap.remove()).toEqual(4);
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});
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});
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describe('when has elements', () => {
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beforeEach(() => {
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heap.add(1);
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heap.add(2);
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heap.add(3);
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heap.add(0);
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});
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describe('#peek', () => {
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it('should get min', () => {
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expect(heap.peek()).toEqual(3);
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});
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});
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describe('#remove', () => {
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it('should get min when duplicates', () => {
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expect(heap.remove()).toEqual(3);
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expect(heap.remove()).toEqual(2);
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expect(heap.remove()).toEqual(1);
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expect(heap.remove()).toEqual(0);
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expect(heap.size()).toBe(0);
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});
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});
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});
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});

‎src/index.js

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@@ -15,6 +15,7 @@ const AvlTree = require('./data-structures/trees/avl-tree');
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const RedBlackTree = require('./data-structures/trees/red-black-tree');
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const LRUCache = require('./data-structures/custom/lru-cache');
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const Trie = require('./data-structures/trees/trie');
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const Heap = require('./data-structures/trees/heap');
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// algorithms
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const bubbleSort = require('./algorithms/sorting/bubble-sort');
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RedBlackTree,
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LRUCache,
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Trie,
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Heap,
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bubbleSort,
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insertionSort,
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selectionSort,

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