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https://github.com/trekhleb/javascript-algorithms.git
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Update Heap.
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@ -1,54 +1,100 @@
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import Comparator from '../../utils/comparator/Comparator';
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export default class MinHeap {
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/**
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* @param {Function} [comparatorFunction]
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*/
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constructor(comparatorFunction) {
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// Array representation of the heap.
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this.heapContainer = [];
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this.compare = new Comparator(comparatorFunction);
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}
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/**
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* @param {number} parentIndex
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* @return {number}
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*/
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static getLeftChildIndex(parentIndex) {
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return (2 * parentIndex) + 1;
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}
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/**
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* @param {number} parentIndex
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* @return {number}
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*/
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static getRightChildIndex(parentIndex) {
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return (2 * parentIndex) + 2;
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}
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/**
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* @param {number} childIndex
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* @return {number}
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*/
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static getParentIndex(childIndex) {
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return Math.floor((childIndex - 1) / 2);
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}
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/**
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* @param {number} childIndex
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* @return {boolean}
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*/
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static hasParent(childIndex) {
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return this.getParentIndex(childIndex) >= 0;
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}
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/**
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* @param {number} parentIndex
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* @return {boolean}
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*/
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hasLeftChild(parentIndex) {
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return MinHeap.getLeftChildIndex(parentIndex) < this.heapContainer.length;
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}
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/**
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* @param {number} parentIndex
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* @return {boolean}
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*/
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hasRightChild(parentIndex) {
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return MinHeap.getRightChildIndex(parentIndex) < this.heapContainer.length;
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}
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/**
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* @param {number} parentIndex
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* @return {*}
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*/
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leftChild(parentIndex) {
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return this.heapContainer[MinHeap.getLeftChildIndex(parentIndex)];
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}
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/**
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* @param {number} parentIndex
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* @return {*}
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*/
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rightChild(parentIndex) {
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return this.heapContainer[MinHeap.getRightChildIndex(parentIndex)];
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}
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/**
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* @param {number} childIndex
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* @return {*}
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*/
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parent(childIndex) {
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return this.heapContainer[MinHeap.getParentIndex(childIndex)];
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}
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/**
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* @param {number} indexOne
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* @param {number} indexTwo
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*/
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swap(indexOne, indexTwo) {
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const tmp = this.heapContainer[indexTwo];
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this.heapContainer[indexTwo] = this.heapContainer[indexOne];
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this.heapContainer[indexOne] = tmp;
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}
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/**
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* @return {*}
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*/
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peek() {
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if (this.heapContainer.length === 0) {
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return null;
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@ -57,6 +103,9 @@ export default class MinHeap {
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return this.heapContainer[0];
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}
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/**
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* @return {*}
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*/
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poll() {
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if (this.heapContainer.length === 0) {
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return null;
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@ -75,11 +124,30 @@ export default class MinHeap {
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return item;
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}
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/**
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* @param {*} item
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*/
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add(item) {
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this.heapContainer.push(item);
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this.heapifyUp();
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}
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/**
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* @param {*} item
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* @return {Number[]}
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*/
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findItem(item) {
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const foundItemIndices = [];
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for (let itemIndex = 0; itemIndex < this.heapContainer.length; itemIndex += 1) {
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if (this.compare.equal(item, this.heapContainer[itemIndex])) {
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foundItemIndices.push(itemIndex);
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}
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}
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return foundItemIndices;
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}
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heapifyUp() {
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// Take last element (last in array or the bottom left in a tree) in
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// a heap container and lift him up until we find the parent element
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@ -120,10 +188,16 @@ export default class MinHeap {
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}
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}
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/**
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* @return {boolean}
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*/
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isEmpty() {
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return !this.heapContainer.length;
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}
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/**
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* @return {string}
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*/
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toString() {
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return this.heapContainer.toString();
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}
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@ -88,4 +88,20 @@ describe('MinHeap', () => {
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expect(minHeap.poll()).toBe(3);
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expect(minHeap.toString()).toBe('10,11,12');
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});
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it('should be possible to find item indices in heap', () => {
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const minHeap = new MinHeap();
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minHeap.add(3);
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minHeap.add(12);
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minHeap.add(10);
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minHeap.add(11);
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minHeap.add(11);
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expect(minHeap.toString()).toBe('3,11,10,12,11');
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expect(minHeap.findItem(5)).toEqual([]);
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expect(minHeap.findItem(3)).toEqual([0]);
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expect(minHeap.findItem(11)).toEqual([1, 4]);
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});
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});
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