mirror of
https://github.moeyy.xyz/https://github.com/trekhleb/javascript-algorithms.git
synced 2024-12-26 07:01:18 +08:00
Add MaxHeap (#167)
* Add MaxHeap * Add parent class for MinHeap and MaxHeap
This commit is contained in:
Oleksii Kersov
Oleksii Trekhleb
parent
a191adeae3
commit
10e633f075
175
src/data-structures/heap/Heap.js
Normal file
175
src/data-structures/heap/Heap.js
Normal file
@ -0,0 +1,175 @@
|
||||
import Comparator from '../../utils/comparator/Comparator';
|
||||
|
||||
/**
|
||||
* Parent class for heaps
|
||||
* @class
|
||||
*/
|
||||
class Heap {
|
||||
/**
|
||||
* @constructs Heap
|
||||
* @param {Function} [comparatorFunction]
|
||||
*/
|
||||
constructor(comparatorFunction) {
|
||||
// Array representation of the heap.
|
||||
this.heapContainer = [];
|
||||
this.compare = new Comparator(comparatorFunction);
|
||||
}
|
||||
|
||||
/**
|
||||
* @param {number} parentIndex
|
||||
* @return {number}
|
||||
*/
|
||||
getLeftChildIndex(parentIndex) {
|
||||
return (2 * parentIndex) + 1;
|
||||
}
|
||||
|
||||
/**
|
||||
* @param {number} parentIndex
|
||||
* @return {number}
|
||||
*/
|
||||
getRightChildIndex(parentIndex) {
|
||||
return (2 * parentIndex) + 2;
|
||||
}
|
||||
|
||||
/**
|
||||
* @param {number} childIndex
|
||||
* @return {number}
|
||||
*/
|
||||
getParentIndex(childIndex) {
|
||||
return Math.floor((childIndex - 1) / 2);
|
||||
}
|
||||
|
||||
/**
|
||||
* @param {number} childIndex
|
||||
* @return {boolean}
|
||||
*/
|
||||
hasParent(childIndex) {
|
||||
return this.getParentIndex(childIndex) >= 0;
|
||||
}
|
||||
|
||||
/**
|
||||
* @param {number} parentIndex
|
||||
* @return {boolean}
|
||||
*/
|
||||
hasLeftChild(parentIndex) {
|
||||
return this.getLeftChildIndex(parentIndex) < this.heapContainer.length;
|
||||
}
|
||||
|
||||
/**
|
||||
* @param {number} parentIndex
|
||||
* @return {boolean}
|
||||
*/
|
||||
hasRightChild(parentIndex) {
|
||||
return this.getRightChildIndex(parentIndex) < this.heapContainer.length;
|
||||
}
|
||||
|
||||
/**
|
||||
* @param {number} parentIndex
|
||||
* @return {*}
|
||||
*/
|
||||
leftChild(parentIndex) {
|
||||
return this.heapContainer[this.getLeftChildIndex(parentIndex)];
|
||||
}
|
||||
|
||||
/**
|
||||
* @param {number} parentIndex
|
||||
* @return {*}
|
||||
*/
|
||||
rightChild(parentIndex) {
|
||||
return this.heapContainer[this.getRightChildIndex(parentIndex)];
|
||||
}
|
||||
|
||||
/**
|
||||
* @param {number} childIndex
|
||||
* @return {*}
|
||||
*/
|
||||
parent(childIndex) {
|
||||
return this.heapContainer[this.getParentIndex(childIndex)];
|
||||
}
|
||||
|
||||
/**
|
||||
* @param {number} indexOne
|
||||
* @param {number} indexTwo
|
||||
*/
|
||||
swap(indexOne, indexTwo) {
|
||||
const tmp = this.heapContainer[indexTwo];
|
||||
this.heapContainer[indexTwo] = this.heapContainer[indexOne];
|
||||
this.heapContainer[indexOne] = tmp;
|
||||
}
|
||||
|
||||
/**
|
||||
* @return {*}
|
||||
*/
|
||||
peek() {
|
||||
if (this.heapContainer.length === 0) {
|
||||
return null;
|
||||
}
|
||||
|
||||
return this.heapContainer[0];
|
||||
}
|
||||
|
||||
/**
|
||||
* @return {*}
|
||||
*/
|
||||
poll() {
|
||||
if (this.heapContainer.length === 0) {
|
||||
return null;
|
||||
}
|
||||
|
||||
if (this.heapContainer.length === 1) {
|
||||
return this.heapContainer.pop();
|
||||
}
|
||||
|
||||
const item = this.heapContainer[0];
|
||||
|
||||
// Move the last element from the end to the head.
|
||||
this.heapContainer[0] = this.heapContainer.pop();
|
||||
this.heapifyDown();
|
||||
|
||||
return item;
|
||||
}
|
||||
|
||||
/**
|
||||
* @param {*} item
|
||||
* @return {MinHeap}
|
||||
*/
|
||||
add(item) {
|
||||
this.heapContainer.push(item);
|
||||
this.heapifyUp();
|
||||
return this;
|
||||
}
|
||||
|
||||
/**
|
||||
* @param {*} item
|
||||
* @param {Comparator} [customComparator]
|
||||
* @return {Number[]}
|
||||
*/
|
||||
find(item, customComparator) {
|
||||
const foundItemIndices = [];
|
||||
const comparator = customComparator || this.compare;
|
||||
|
||||
for (let itemIndex = 0; itemIndex < this.heapContainer.length; itemIndex += 1) {
|
||||
if (comparator.equal(item, this.heapContainer[itemIndex])) {
|
||||
foundItemIndices.push(itemIndex);
|
||||
}
|
||||
}
|
||||
|
||||
return foundItemIndices;
|
||||
}
|
||||
|
||||
/**
|
||||
* @return {boolean}
|
||||
*/
|
||||
isEmpty() {
|
||||
return !this.heapContainer.length;
|
||||
}
|
||||
|
||||
/**
|
||||
* @return {string}
|
||||
*/
|
||||
toString() {
|
||||
return this.heapContainer.toString();
|
||||
}
|
||||
}
|
||||
|
||||
export default Heap;
|
||||
104
src/data-structures/heap/MaxHeap.js
Normal file
104
src/data-structures/heap/MaxHeap.js
Normal file
@ -0,0 +1,104 @@
|
||||
import Heap from './Heap';
|
||||
|
||||
/**
|
||||
* Creates a new MaxHeap
|
||||
* @class
|
||||
* @augments Heap
|
||||
*/
|
||||
class MaxHeap extends Heap {
|
||||
/**
|
||||
* @param {*} item
|
||||
* @param {Comparator} [customFindingComparator]
|
||||
* @return {MaxHeap}
|
||||
*/
|
||||
remove(item, customFindingComparator) {
|
||||
// Find number of items to remove.
|
||||
const customComparator = customFindingComparator || this.compare;
|
||||
const numberOfItemsToRemove = this.find(item, customComparator).length;
|
||||
|
||||
for (let iteration = 0; iteration < numberOfItemsToRemove; iteration += 1) {
|
||||
// We need to find item index to remove each time after removal since
|
||||
// indices are being change after each heapify process.
|
||||
const indexToRemove = this.find(item, customComparator).pop();
|
||||
|
||||
// If we need to remove last child in the heap then just remove it.
|
||||
// There is no need to heapify the heap afterwards.
|
||||
if (indexToRemove === (this.heapContainer.length - 1)) {
|
||||
this.heapContainer.pop();
|
||||
} else {
|
||||
// Move last element in heap to the vacant (removed) position.
|
||||
this.heapContainer[indexToRemove] = this.heapContainer.pop();
|
||||
|
||||
// Get parent.
|
||||
const parentItem = this.hasParent(indexToRemove) ? this.parent(indexToRemove) : null;
|
||||
const leftChild = this.hasLeftChild(indexToRemove) ? this.leftChild(indexToRemove) : null;
|
||||
|
||||
// If there is no parent or parent is greater then node to delete then heapify down.
|
||||
// Otherwise heapify up.
|
||||
if (
|
||||
leftChild !== null
|
||||
&& (
|
||||
parentItem === null
|
||||
|| this.compare.greaterThan(parentItem, this.heapContainer[indexToRemove])
|
||||
)
|
||||
) {
|
||||
this.heapifyDown(indexToRemove);
|
||||
} else {
|
||||
this.heapifyUp(indexToRemove);
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
return this;
|
||||
}
|
||||
|
||||
/**
|
||||
* @param {number} [customStartIndex]
|
||||
*/
|
||||
heapifyUp(customStartIndex) {
|
||||
// Take last element (last in array or the bottom left in a tree) in
|
||||
// a heap container and lift him up until we find the parent element
|
||||
// that is greater then the current new one.
|
||||
let currentIndex = customStartIndex || this.heapContainer.length - 1;
|
||||
|
||||
while (
|
||||
this.hasParent(currentIndex)
|
||||
&& this.compare.greaterThan(this.heapContainer[currentIndex], this.parent(currentIndex))
|
||||
) {
|
||||
this.swap(currentIndex, this.getParentIndex(currentIndex));
|
||||
currentIndex = this.getParentIndex(currentIndex);
|
||||
}
|
||||
}
|
||||
|
||||
/**
|
||||
* @param {number} [customStartIndex]
|
||||
*/
|
||||
heapifyDown(customStartIndex) {
|
||||
// Compare the root element to its children and swap root with the smallest
|
||||
// of children. Do the same for next children after swap.
|
||||
let currentIndex = customStartIndex || 0;
|
||||
let nextIndex = null;
|
||||
|
||||
while (this.hasLeftChild(currentIndex)) {
|
||||
if (
|
||||
this.hasRightChild(currentIndex)
|
||||
&& this.compare.greaterThan(this.rightChild(currentIndex), this.leftChild(currentIndex))
|
||||
) {
|
||||
nextIndex = this.getRightChildIndex(currentIndex);
|
||||
} else {
|
||||
nextIndex = this.getLeftChildIndex(currentIndex);
|
||||
}
|
||||
|
||||
if (
|
||||
this.compare.greaterThan(this.heapContainer[currentIndex], this.heapContainer[nextIndex])
|
||||
) {
|
||||
break;
|
||||
}
|
||||
|
||||
this.swap(currentIndex, nextIndex);
|
||||
currentIndex = nextIndex;
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
export default MaxHeap;
|
||||
@ -1,139 +1,11 @@
|
||||
import Comparator from '../../utils/comparator/Comparator';
|
||||
|
||||
export default class MinHeap {
|
||||
/**
|
||||
* @param {Function} [comparatorFunction]
|
||||
*/
|
||||
constructor(comparatorFunction) {
|
||||
// Array representation of the heap.
|
||||
this.heapContainer = [];
|
||||
this.compare = new Comparator(comparatorFunction);
|
||||
}
|
||||
|
||||
/**
|
||||
* @param {number} parentIndex
|
||||
* @return {number}
|
||||
*/
|
||||
getLeftChildIndex(parentIndex) {
|
||||
return (2 * parentIndex) + 1;
|
||||
}
|
||||
|
||||
/**
|
||||
* @param {number} parentIndex
|
||||
* @return {number}
|
||||
*/
|
||||
getRightChildIndex(parentIndex) {
|
||||
return (2 * parentIndex) + 2;
|
||||
}
|
||||
|
||||
/**
|
||||
* @param {number} childIndex
|
||||
* @return {number}
|
||||
*/
|
||||
getParentIndex(childIndex) {
|
||||
return Math.floor((childIndex - 1) / 2);
|
||||
}
|
||||
|
||||
/**
|
||||
* @param {number} childIndex
|
||||
* @return {boolean}
|
||||
*/
|
||||
hasParent(childIndex) {
|
||||
return this.getParentIndex(childIndex) >= 0;
|
||||
}
|
||||
|
||||
/**
|
||||
* @param {number} parentIndex
|
||||
* @return {boolean}
|
||||
*/
|
||||
hasLeftChild(parentIndex) {
|
||||
return this.getLeftChildIndex(parentIndex) < this.heapContainer.length;
|
||||
}
|
||||
|
||||
/**
|
||||
* @param {number} parentIndex
|
||||
* @return {boolean}
|
||||
*/
|
||||
hasRightChild(parentIndex) {
|
||||
return this.getRightChildIndex(parentIndex) < this.heapContainer.length;
|
||||
}
|
||||
|
||||
/**
|
||||
* @param {number} parentIndex
|
||||
* @return {*}
|
||||
*/
|
||||
leftChild(parentIndex) {
|
||||
return this.heapContainer[this.getLeftChildIndex(parentIndex)];
|
||||
}
|
||||
|
||||
/**
|
||||
* @param {number} parentIndex
|
||||
* @return {*}
|
||||
*/
|
||||
rightChild(parentIndex) {
|
||||
return this.heapContainer[this.getRightChildIndex(parentIndex)];
|
||||
}
|
||||
|
||||
/**
|
||||
* @param {number} childIndex
|
||||
* @return {*}
|
||||
*/
|
||||
parent(childIndex) {
|
||||
return this.heapContainer[this.getParentIndex(childIndex)];
|
||||
}
|
||||
|
||||
/**
|
||||
* @param {number} indexOne
|
||||
* @param {number} indexTwo
|
||||
*/
|
||||
swap(indexOne, indexTwo) {
|
||||
const tmp = this.heapContainer[indexTwo];
|
||||
this.heapContainer[indexTwo] = this.heapContainer[indexOne];
|
||||
this.heapContainer[indexOne] = tmp;
|
||||
}
|
||||
|
||||
/**
|
||||
* @return {*}
|
||||
*/
|
||||
peek() {
|
||||
if (this.heapContainer.length === 0) {
|
||||
return null;
|
||||
}
|
||||
|
||||
return this.heapContainer[0];
|
||||
}
|
||||
|
||||
/**
|
||||
* @return {*}
|
||||
*/
|
||||
poll() {
|
||||
if (this.heapContainer.length === 0) {
|
||||
return null;
|
||||
}
|
||||
|
||||
if (this.heapContainer.length === 1) {
|
||||
return this.heapContainer.pop();
|
||||
}
|
||||
|
||||
const item = this.heapContainer[0];
|
||||
|
||||
// Move the last element from the end to the head.
|
||||
this.heapContainer[0] = this.heapContainer.pop();
|
||||
this.heapifyDown();
|
||||
|
||||
return item;
|
||||
}
|
||||
|
||||
/**
|
||||
* @param {*} item
|
||||
* @return {MinHeap}
|
||||
*/
|
||||
add(item) {
|
||||
this.heapContainer.push(item);
|
||||
this.heapifyUp();
|
||||
return this;
|
||||
}
|
||||
import Heap from './Heap';
|
||||
|
||||
/**
|
||||
* Creates a new MinHeap
|
||||
* @class
|
||||
* @augments Heap
|
||||
*/
|
||||
class MinHeap extends Heap {
|
||||
/**
|
||||
* @param {*} item
|
||||
* @param {Comparator} [customFindingComparator]
|
||||
@ -180,24 +52,6 @@ export default class MinHeap {
|
||||
return this;
|
||||
}
|
||||
|
||||
/**
|
||||
* @param {*} item
|
||||
* @param {Comparator} [customComparator]
|
||||
* @return {Number[]}
|
||||
*/
|
||||
find(item, customComparator) {
|
||||
const foundItemIndices = [];
|
||||
const comparator = customComparator || this.compare;
|
||||
|
||||
for (let itemIndex = 0; itemIndex < this.heapContainer.length; itemIndex += 1) {
|
||||
if (comparator.equal(item, this.heapContainer[itemIndex])) {
|
||||
foundItemIndices.push(itemIndex);
|
||||
}
|
||||
}
|
||||
|
||||
return foundItemIndices;
|
||||
}
|
||||
|
||||
/**
|
||||
* @param {number} [customStartIndex]
|
||||
*/
|
||||
@ -243,18 +97,6 @@ export default class MinHeap {
|
||||
currentIndex = nextIndex;
|
||||
}
|
||||
}
|
||||
|
||||
/**
|
||||
* @return {boolean}
|
||||
*/
|
||||
isEmpty() {
|
||||
return !this.heapContainer.length;
|
||||
}
|
||||
|
||||
/**
|
||||
* @return {string}
|
||||
*/
|
||||
toString() {
|
||||
return this.heapContainer.toString();
|
||||
}
|
||||
}
|
||||
|
||||
export default MinHeap;
|
||||
|
||||
172
src/data-structures/heap/__test__/MaxHeap.test.js
Normal file
172
src/data-structures/heap/__test__/MaxHeap.test.js
Normal file
@ -0,0 +1,172 @@
|
||||
import MaxHeap from '../MaxHeap';
|
||||
import Comparator from '../../../utils/comparator/Comparator';
|
||||
|
||||
describe('MaxHeap', () => {
|
||||
it('should create an empty max heap', () => {
|
||||
const maxHeap = new MaxHeap();
|
||||
|
||||
expect(maxHeap).toBeDefined();
|
||||
expect(maxHeap.peek()).toBeNull();
|
||||
expect(maxHeap.isEmpty()).toBe(true);
|
||||
});
|
||||
|
||||
it('should add items to the heap and heapify it up', () => {
|
||||
const maxHeap = new MaxHeap();
|
||||
|
||||
maxHeap.add(5);
|
||||
expect(maxHeap.isEmpty()).toBe(false);
|
||||
expect(maxHeap.peek()).toBe(5);
|
||||
expect(maxHeap.toString()).toBe('5');
|
||||
|
||||
maxHeap.add(3);
|
||||
expect(maxHeap.peek()).toBe(5);
|
||||
expect(maxHeap.toString()).toBe('5,3');
|
||||
|
||||
maxHeap.add(10);
|
||||
expect(maxHeap.peek()).toBe(10);
|
||||
expect(maxHeap.toString()).toBe('10,3,5');
|
||||
|
||||
maxHeap.add(1);
|
||||
expect(maxHeap.peek()).toBe(10);
|
||||
expect(maxHeap.toString()).toBe('10,3,5,1');
|
||||
|
||||
maxHeap.add(1);
|
||||
expect(maxHeap.peek()).toBe(10);
|
||||
expect(maxHeap.toString()).toBe('10,3,5,1,1');
|
||||
|
||||
expect(maxHeap.poll()).toBe(10);
|
||||
expect(maxHeap.toString()).toBe('5,3,1,1');
|
||||
|
||||
expect(maxHeap.poll()).toBe(5);
|
||||
expect(maxHeap.toString()).toBe('3,1,1');
|
||||
|
||||
expect(maxHeap.poll()).toBe(3);
|
||||
expect(maxHeap.toString()).toBe('1,1');
|
||||
});
|
||||
|
||||
it('should poll items from the heap and heapify it down', () => {
|
||||
const maxHeap = new MaxHeap();
|
||||
|
||||
maxHeap.add(5);
|
||||
maxHeap.add(3);
|
||||
maxHeap.add(10);
|
||||
maxHeap.add(11);
|
||||
maxHeap.add(1);
|
||||
|
||||
expect(maxHeap.toString()).toBe('11,10,5,3,1');
|
||||
|
||||
expect(maxHeap.poll()).toBe(11);
|
||||
expect(maxHeap.toString()).toBe('10,3,5,1');
|
||||
|
||||
expect(maxHeap.poll()).toBe(10);
|
||||
expect(maxHeap.toString()).toBe('5,3,1');
|
||||
|
||||
expect(maxHeap.poll()).toBe(5);
|
||||
expect(maxHeap.toString()).toBe('3,1');
|
||||
|
||||
expect(maxHeap.poll()).toBe(3);
|
||||
expect(maxHeap.toString()).toBe('1');
|
||||
|
||||
expect(maxHeap.poll()).toBe(1);
|
||||
expect(maxHeap.toString()).toBe('');
|
||||
|
||||
expect(maxHeap.poll()).toBeNull();
|
||||
expect(maxHeap.toString()).toBe('');
|
||||
});
|
||||
|
||||
it('should heapify down through the right branch as well', () => {
|
||||
const maxHeap = new MaxHeap();
|
||||
|
||||
maxHeap.add(3);
|
||||
maxHeap.add(12);
|
||||
maxHeap.add(10);
|
||||
|
||||
expect(maxHeap.toString()).toBe('12,3,10');
|
||||
|
||||
maxHeap.add(11);
|
||||
expect(maxHeap.toString()).toBe('12,11,10,3');
|
||||
|
||||
expect(maxHeap.poll()).toBe(12);
|
||||
expect(maxHeap.toString()).toBe('11,3,10');
|
||||
});
|
||||
|
||||
it('should be possible to find item indices in heap', () => {
|
||||
const maxHeap = new MaxHeap();
|
||||
|
||||
maxHeap.add(3);
|
||||
maxHeap.add(12);
|
||||
maxHeap.add(10);
|
||||
maxHeap.add(11);
|
||||
maxHeap.add(11);
|
||||
|
||||
expect(maxHeap.toString()).toBe('12,11,10,3,11');
|
||||
|
||||
expect(maxHeap.find(5)).toEqual([]);
|
||||
expect(maxHeap.find(12)).toEqual([0]);
|
||||
expect(maxHeap.find(11)).toEqual([1, 4]);
|
||||
});
|
||||
|
||||
it('should be possible to remove items from heap with heapify down', () => {
|
||||
const maxHeap = new MaxHeap();
|
||||
|
||||
maxHeap.add(3);
|
||||
maxHeap.add(12);
|
||||
maxHeap.add(10);
|
||||
maxHeap.add(11);
|
||||
maxHeap.add(11);
|
||||
|
||||
expect(maxHeap.toString()).toBe('12,11,10,3,11');
|
||||
|
||||
expect(maxHeap.remove(12).toString()).toEqual('11,11,10,3');
|
||||
expect(maxHeap.remove(12).peek()).toEqual(11);
|
||||
expect(maxHeap.remove(11).toString()).toEqual('10,3');
|
||||
expect(maxHeap.remove(10).peek()).toEqual(3);
|
||||
});
|
||||
|
||||
it('should be possible to remove items from heap with heapify up', () => {
|
||||
const maxHeap = new MaxHeap();
|
||||
|
||||
maxHeap.add(3);
|
||||
maxHeap.add(10);
|
||||
maxHeap.add(5);
|
||||
maxHeap.add(6);
|
||||
maxHeap.add(7);
|
||||
maxHeap.add(4);
|
||||
maxHeap.add(6);
|
||||
maxHeap.add(8);
|
||||
maxHeap.add(2);
|
||||
maxHeap.add(1);
|
||||
|
||||
expect(maxHeap.toString()).toBe('10,8,6,7,6,4,5,3,2,1');
|
||||
expect(maxHeap.remove(4).toString()).toEqual('10,8,6,7,6,1,5,3,2');
|
||||
expect(maxHeap.remove(3).toString()).toEqual('10,8,6,7,6,1,5,2');
|
||||
expect(maxHeap.remove(5).toString()).toEqual('10,8,6,7,6,1,2');
|
||||
expect(maxHeap.remove(10).toString()).toEqual('8,7,6,2,6,1');
|
||||
expect(maxHeap.remove(6).toString()).toEqual('8,7,1,2');
|
||||
expect(maxHeap.remove(2).toString()).toEqual('8,7,1');
|
||||
expect(maxHeap.remove(1).toString()).toEqual('8,7');
|
||||
expect(maxHeap.remove(7).toString()).toEqual('8');
|
||||
expect(maxHeap.remove(8).toString()).toEqual('');
|
||||
});
|
||||
|
||||
it('should be possible to remove items from heap with custom finding comparator', () => {
|
||||
const maxHeap = new MaxHeap();
|
||||
maxHeap.add('a');
|
||||
maxHeap.add('bb');
|
||||
maxHeap.add('ccc');
|
||||
maxHeap.add('dddd');
|
||||
|
||||
expect(maxHeap.toString()).toBe('dddd,ccc,bb,a');
|
||||
|
||||
const comparator = new Comparator((a, b) => {
|
||||
if (a.length === b.length) {
|
||||
return 0;
|
||||
}
|
||||
|
||||
return a.length < b.length ? -1 : 1;
|
||||
});
|
||||
|
||||
maxHeap.remove('hey', comparator);
|
||||
expect(maxHeap.toString()).toBe('dddd,a,bb');
|
||||
});
|
||||
});
|
||||
Loading…
Reference in New Issue
Block a user