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Move common Max/Min Heap code to Heap.js.

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This commit is contained in:
Oleksii Trekhleb 2018-08-17 10:23:07 +03:00
parent 031c5da556
commit a02d5f625d
3 changed files with 126 additions and 182 deletions
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112
src/data-structures/heap/Heap.js
View File

@ -142,6 +142,52 @@ export default class Heap {
return this;
}
/**
* @param {*} item
* @param {Comparator} [customFindingComparator]
* @return {Heap}
*/
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 in incorrect order with the node
// we're going to delete then heapify down. Otherwise heapify up.
if (
leftChild !== null
&& (
parentItem === null
|| !this.pairIsInCorrectOrder(parentItem, this.heapContainer[indexToRemove])
)
) {
this.heapifyDown(indexToRemove);
} else {
this.heapifyUp(indexToRemove);
}
}
}
return this;
}
/**
* @param {*} item
* @param {Comparator} [customComparator]
@ -174,11 +220,69 @@ export default class Heap {
return this.heapContainer.toString();
}
heapifyUp() {
throw new Error('You have to implement this method!');
/**
* @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 less then the current new one.
let currentIndex = customStartIndex || this.heapContainer.length - 1;
while (
this.hasParent(currentIndex)
&& !this.pairIsInCorrectOrder(this.parent(currentIndex), this.heapContainer[currentIndex])
) {
this.swap(currentIndex, this.getParentIndex(currentIndex));
currentIndex = this.getParentIndex(currentIndex);
}
}
heapifyDown() {
throw new Error('You have to implement this method!');
/**
* @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.pairIsInCorrectOrder(this.rightChild(currentIndex), this.leftChild(currentIndex))
) {
nextIndex = this.getRightChildIndex(currentIndex);
} else {
nextIndex = this.getLeftChildIndex(currentIndex);
}
if (!this.pairIsInCorrectOrder(
this.heapContainer[nextIndex],
this.heapContainer[currentIndex],
)) {
break;
}
this.swap(currentIndex, nextIndex);
currentIndex = nextIndex;
}
}
/**
* Checks if pair of heap elements is in correct order.
* For MinHeap the first element must be always smaller or equal.
* For MaxHeap the first element must be always bigger or equal.
*
* @param {*} firstElement
* @param {*} secondElement
* @return {boolean}
*/
/* istanbul ignore next */
pairIsInCorrectOrder(firstElement, secondElement) {
throw new Error(`
You have to implement heap pair comparision method
for ${firstElement} and ${secondElement} values.
`);
}
}

99
src/data-structures/heap/MaxHeap.js
View File

@ -2,96 +2,15 @@ import Heap from './Heap';
export default class MaxHeap extends Heap {
/**
* @param {*} item
* @param {Comparator} [customFindingComparator]
* @return {MaxHeap}
* Checks if pair of heap elements is in correct order.
* For MinHeap the first element must be always smaller or equal.
* For MaxHeap the first element must be always bigger or equal.
*
* @param {*} firstElement
* @param {*} secondElement
* @return {boolean}
*/
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 biggest
// 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;
}
pairIsInCorrectOrder(firstElement, secondElement) {
return this.compare.greaterThanOrEqual(firstElement, secondElement);
}
}

97
src/data-structures/heap/MinHeap.js
View File

@ -2,94 +2,15 @@ import Heap from './Heap';
export default class MinHeap extends Heap {
/**
* @param {*} item
* @param {Comparator} [customFindingComparator]
* @return {MinHeap}
* Checks if pair of heap elements is in correct order.
* For MinHeap the first element must be always smaller or equal.
* For MaxHeap the first element must be always bigger or equal.
*
* @param {*} firstElement
* @param {*} secondElement
* @return {boolean}
*/
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 less then node to delete then heapify down.
// Otherwise heapify up.
if (
leftChild !== null
&& (
parentItem === null
|| this.compare.lessThan(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 less then the current new one.
let currentIndex = customStartIndex || this.heapContainer.length - 1;
while (
this.hasParent(currentIndex)
&& this.compare.lessThan(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.lessThan(this.rightChild(currentIndex), this.leftChild(currentIndex))
) {
nextIndex = this.getRightChildIndex(currentIndex);
} else {
nextIndex = this.getLeftChildIndex(currentIndex);
}
if (this.compare.lessThan(this.heapContainer[currentIndex], this.heapContainer[nextIndex])) {
break;
}
this.swap(currentIndex, nextIndex);
currentIndex = nextIndex;
}
pairIsInCorrectOrder(firstElement, secondElement) {
return this.compare.lessThanOrEqual(firstElement, secondElement);
}
}