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Commit 4cc4578

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Linked List
1 parent c752849 commit 4cc4578

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3 files changed

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3 files changed

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‎#9 - Linked List/1-linked-list.js‎

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// Linked List in Javascript
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class Node {
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constructor(data) {
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this.data = data;
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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 = null;
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}
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addFirst(data) {
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const newNode = new Node(data);
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newNode.next = this.head;
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this.head = newNode;
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}
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addLast(data) {
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const newNode = new Node(data);
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if (!this.head) {
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this.head = newNode;
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return;
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}
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let current = this.head;
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while (current.next) {
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current = current.next;
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}
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current.next = newNode;
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}
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size() {
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let count = 0;
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let current = this.head;
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while (current) {
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count++;
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current = current.next;
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}
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return count;
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}
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addAt(index, data) {
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if (index < 0 || index > this.size()) {
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console.error("Invalid Index");
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return;
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}
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const newNode = new Node(data);
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if (index === 0) {
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newNode.next = this.head;
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this.head = newNode;
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return;
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}
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let current = this.head;
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for (let i = 0; i < index - 1; i++) {
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current = current.next;
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}
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newNode.next = current.next;
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current.next = newNode;
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}
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removeTop() {
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if (!this.head) {
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return;
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}
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this.head = this.head.next;
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}
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removeLast() {
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if (!this.head) {
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return;
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}
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let current = this.head;
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while (current.next.next) {
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current = current.next;
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}
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current.next = null;
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}
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removeAt(index) {
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if (index < 0 || index > this.size()) {
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console.error("Invalid Index");
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return;
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}
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if (index === 0) {
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this.head = this.head.next;
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return;
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}
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let current = this.head;
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for (let i = 0; i < index - 1; i++) {
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current = current.next;
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}
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if (current.next) {
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current.next = current.next.next;
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}
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}
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print() {
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let current = this.head;
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while (current) {
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console.log(current.data);
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current = current.next;
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}
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}
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}
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const linkedlist = new LinkedList();
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linkedlist.addFirst(5);
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linkedlist.addFirst(3);
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linkedlist.addFirst(8);
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linkedlist.addLast(6);
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linkedlist.removeTop();
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linkedlist.addAt(2, 8);
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linkedlist.removeLast();
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linkedlist.removeAt(2);
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linkedlist.print();
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console.log("size = " + linkedlist.size());
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// Ques 1 : Given the head of a singly linked list, return true if it is
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// a palindrome or false otherwise
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// Input: head = [1,2,2,1] ----->>>>> Output: true;
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// Input: head = [1,2] ----->>>>> Output: false;
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/**
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* Definition for singly-linked list.
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* function ListNode(val, next) {
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* this.val = (val===undefined ? 0 : val)
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* this.next = (next===undefined ? null : next)
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* }
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*/
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var isPalindrome = function (head) {
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let string1 = (string2 = "");
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let node = head;
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while (node != null) {
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string1 = `${string1}${node.val}`;
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string2 = `${node.val}${string2}`;
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node = node.next;
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}
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return string1 === string2;
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};
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// Ques 2 : Given the head of a singly linked list, reverse the list, and
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// return the reversed list.
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// Input: head = [1,2] ----->>>>> Output: [2,1];
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/**
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* Definition for singly-linked list.
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* function ListNode(val, next) {
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* this.val = (val===undefined ? 0 : val)
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* this.next = (next===undefined ? null : next)
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* }
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*/
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var reverseList = (head) => {
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let prev = null;
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let current = head;
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while (current !== null) {
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const nextNode = current.next;
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current.next = prev;
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prev = current;
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current = nextNode;
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}
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return prev;
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};

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