doubly linked list | JavaScript

December 24th, 2021 07:32:43 PM

					
class DoublyLinkedList { constructor() { this.nodes = []; } get size() { return this.nodes.length; } get head() { return this.size ? this.nodes[0] : null; } get tail() { return this.size ? this.nodes[this.size - 1] : null; } insertAt(index, value) { const previousNode = this.nodes[index - 1] || null; const nextNode = this.nodes[index] || null; const node = { value, next: nextNode, previous: previousNode }; if (previousNode) previousNode.next = node; if (nextNode) nextNode.previous = node; this.nodes.splice(index, 0, node); } insertFirst(value) { this.insertAt(0, value); } insertLast(value) { this.insertAt(this.size, value); } getAt(index) { return this.nodes[index]; } removeAt(index) { const previousNode = this.nodes[index - 1] || null; const nextNode = this.nodes[index + 1] || null; if (previousNode) previousNode.next = nextNode; if (nextNode) nextNode.previous = previousNode; return this.nodes.splice(index, 1); } clear() { this.nodes = []; } reverse() { this.nodes = this.nodes.reduce((acc, { value }) => { const nextNode = acc[0] || null; const node = { value, next: nextNode, previous: null }; if (nextNode) nextNode.previous = node; return [node, ...acc]; }, []); } *[Symbol.iterator]() { yield* this.nodes; } } const list = new DoublyLinkedList(); list.insertFirst(1); list.insertFirst(2); list.insertFirst(3); list.insertLast(4); list.insertAt(3, 5); list.size; // 5 list.head.value; // 3 list.head.next.value; // 2 list.tail.value; // 4 list.tail.previous.value; // 5 [...list.map(e => e.value)]; // [3, 2, 1, 5, 4] list.removeAt(1); // 2 list.getAt(1).value; // 1 list.head.next.value; // 1 [...list.map(e => e.value)]; // [3, 1, 5, 4] list.reverse(); [...list.map(e => e.value)]; // [4, 5, 1, 3] list.clear(); list.size; // 0

Featured Posts