class MyDoubleLinkedList {
constructor(value) {
this.head = {
value,
next: null,
previous: null
}
this.tail = this.head;
this.length = 1;
}
newNode(value) {
return {
value,
next: null,
previous: null
};
}
append(value) {
const node = this.newNode(value);
if(this.tail === null) {
this.tail = node;
this.head = this.tail;
}else {
this.tail.next = node;
node.previous = this.tail;
this.tail = node;
}
this.length++;
}
prepend(value) {
const node = this.newNode(value);
if(this.head === null) {
this.head = node;
this.tail = this.head;
}else {
node.next = this.head;
this.head.previous = node;
this.head = node;
}
this.length++;
}
insertNode(value, index) {
if(index >= this.length) {
this.append(value);
}else if(index <= 0) {
this.prepend(value);
}else {
const node = this.newNode(value);
const prevNode = this.traversal(index-1);
const nextNode = prevNode.next;
prevNode.next = node;
nextNode.previous = node;
node.previous = prevNode;
node.next = nextNode;
this.length++;
}
}
deleteNode(index) {
if(this.length === 0 || index < 0 || index >= this.length) {
return false;
}else {
if(index === 0) {
if(this.length === 1) {
this.head = null;
this.tail = null;
this.length = 0;
}else {
const removedNode = this.head;
this.head = this.head.next;
this.head.previous = null;
removedNode.next = null;
this.length--;
}
}else {
const prevNode = this.traversal(index-1);
const nextNode = prevNode.next;
prevNode.next = nextNode.next;
nextNode.next = null;
nextNode.previous = null;
this.length--;
if(nextNode === this.tail) {
this.tail = prevNode;
}else {
prevNode.next.previous = prevNode;
}
}
return true;
}
}
traversal(index) {
// Need to change based on index value
// If index is less than half of the length then start from 0 otherwise start from end
let current = this.head;
for(let i=0;i < index && current !== null;i++) {
current = current.next;
}
return current;
}
}
const firstLinkedList = new MyDoubleLinkedList(10);
firstLinkedList.append(5);
firstLinkedList.append(16);
firstLinkedList.prepend(1);
console.log(firstLinkedList.deleteNode(1));
firstLinkedList.insertNode(3, 1);
console.log(firstLinkedList);
