75 lines
2.1 KiB
JavaScript
75 lines
2.1 KiB
JavaScript
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// https://www.freecodecamp.org/learn/coding-interview-prep/data-structures/create-a-priority-queue-class
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function PriorityQueue() {
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this.collection = [];
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this.printCollection = function () {
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console.log(
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this.collection.map(([elem, priority, order]) => [elem, priority])
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);
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};
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// Only change code below this line
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this.order = 0;
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this.size = function () {
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return this.collection.length;
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};
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this.isEmpty = function () {
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return !this.collection.length;
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};
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this.swap = function (a, b) {
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const tmp = this.collection[a];
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this.collection[a] = this.collection[b];
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this.collection[b] = tmp;
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};
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this.changePriority = function (a, b) {
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return (
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this.collection[a][1] > this.collection[b][1] ||
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(this.collection[a][1] == this.collection[b][1] &&
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this.collection[a][2] > this.collection[b][2])
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);
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};
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this.enqueue = function (elem) {
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elem.push(this.order++);
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this.collection.push(elem);
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let me = this.collection.length - 1;
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let parent = Math.trunc((me - 1) / 2);
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while (this.changePriority(parent, me)) {
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this.swap(parent, me);
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me = parent;
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parent = Math.trunc((me - 1) / 2);
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}
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};
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this.dequeue = function () {
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if (this.isEmpty()) return;
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this.swap(0, this.collection.length - 1);
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const elem = this.collection.pop()[0];
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let me = 0;
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let leftChild = me * 2 + 1;
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let rightChild = leftChild + 1;
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while (
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(leftChild < this.collection.length &&
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this.changePriority(me, leftChild)) ||
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(rightChild < this.collection.length &&
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this.changePriority(me, rightChild))
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) {
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if (
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rightChild < this.collection.length &&
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this.changePriority(leftChild, rightChild)
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) {
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this.swap(me, rightChild);
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me = rightChild;
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} else {
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this.swap(me, leftChild);
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me = leftChild;
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}
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leftChild = me * 2 + 1;
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rightChild = leftChild + 1;
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}
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return elem;
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};
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this.front = function () {
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if (this.isEmpty()) return;
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return this.collection[0][0];
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};
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// Only change code above this line
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}
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