mirror of https://github.com/jkjoy/sunpeiwen.git
68 lines
1.2 KiB
JavaScript
68 lines
1.2 KiB
JavaScript
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/*
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How it works:
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`this.#head` is an instance of `Node` which keeps track of its current value and nests another instance of `Node` that keeps the value that comes after it. When a value is provided to `.enqueue()`, the code needs to iterate through `this.#head`, going deeper and deeper to find the last value. However, iterating through every single item is slow. This problem is solved by saving a reference to the last value as `this.#tail` so that it can reference it to add a new value.
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*/
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class Node {
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value;
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next;
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constructor(value) {
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this.value = value;
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}
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}
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export default class Queue {
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#head;
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#tail;
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#size;
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constructor() {
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this.clear();
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}
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enqueue(value) {
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const node = new Node(value);
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if (this.#head) {
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this.#tail.next = node;
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this.#tail = node;
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} else {
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this.#head = node;
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this.#tail = node;
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}
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this.#size++;
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}
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dequeue() {
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const current = this.#head;
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if (!current) {
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return;
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}
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this.#head = this.#head.next;
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this.#size--;
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return current.value;
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}
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clear() {
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this.#head = undefined;
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this.#tail = undefined;
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this.#size = 0;
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}
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get size() {
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return this.#size;
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}
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* [Symbol.iterator]() {
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let current = this.#head;
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while (current) {
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yield current.value;
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current = current.next;
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}
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}
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}
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