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Commit bede2a5

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Doubly Linked List 😉
1 parent f8ae8ee commit bede2a5

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2 files changed

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2 files changed

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class Node {
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constructor(data) {
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this.data = data;
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this.prev = null;
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this.next = null;
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}
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}
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class LinkedList {
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constructor() {
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this.head = new Node("head");
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}
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find(data) {
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let temp = this.head;
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while(temp.data != data)
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temp = temp.next;
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return temp;
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}
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findLast() {
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let temp = this.head;
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while(temp.next != null)
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temp = temp.next;
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return temp;
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}
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printList() {
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let temp = this.head;
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if(temp.next == null)
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return "The Linked List is Empty";
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let str = "";
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while(temp.next != null) {
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str += temp.next.data + " -> ";
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temp = temp.next;
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}
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str += "NULL\n";
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return str;
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}
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printListReverse() {
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let temp = this.findLast();
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if(temp.prev == null)
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return "The Linked List is Empty";
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let str = "";
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while(temp.prev != null) {
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str += temp.data + " -> ";
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temp = temp.prev;
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}
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str += "NULL\n";
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return str;
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}
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insertAfter(data,currData) {
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const newNode = new Node(data);
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let curr = this.find(currData);
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newNode.next = curr.next;
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newNode.prev = curr;
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curr.next = newNode;
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}
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remove(data) {
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const curr = this.find(data);
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if(curr.next != null) {
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curr.prev.next = curr.next;
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curr.next.prev = curr.prev;
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curr.prev = null;
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curr.next = null;
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}
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else this.head.next = null;
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}
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}
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module.exports = LinkedList;
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const expect = require('chai').expect;
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const DoublyLinkedList = require('../../examples/datastructures/doubly-linked-list');
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describe('=> DOUBLY LINKED LIST', function() {
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let names;
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before(function () {
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names = new DoublyLinkedList();
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});
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it('should create an Empty Linked List', function(done) {
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expect(names.head.data).to.equal("head");
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done();
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});
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it('should print an Empty Linked List', function(done) {
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expect(names.printList()).to.equal("The Linked List is Empty");
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done();
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});
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it('should insert into a Linked List', function(done) {
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names.insertAfter(1,"head");
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names.insertAfter(2, 1);
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names.insertAfter(3, 2);
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names.insertAfter(4, 3);
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expect(names.printList()).to.equal("1 -> 2 -> 3 -> 4 -> NULL\n");
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expect(names.printListReverse()).to.equal("4 -> 3 -> 2 -> 1 -> NULL\n");
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done();
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});
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it('should remove element from a Linked List', function(done) {
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names.remove(1);
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expect(names.printList()).to.equal("2 -> 3 -> 4 -> NULL\n");
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expect(names.printListReverse()).to.equal("4 -> 3 -> 2 -> NULL\n");
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done();
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});
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describe('=> clear', function() {
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it('should clear the Linked List', function(done) {
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names.remove(2);
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names.remove(3);
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names.remove(4);
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expect(names.printList()).to.equal("The Linked List is Empty");
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done();
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});
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});
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});

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