class MyLinkedList {
constructor(value) {
if(value === undefined) {
this.head = null;
this.length = 0;
}else {
this.head = {
value,
next: null
}
this.length = 1;
}
this.tail = this.head;
}
newNode(value) {
return {
value,
next: null
};
}
append(value) {
const node = this.newNode(value);
if(this.tail === null) {
this.tail = node;
this.head = this.tail;
}else {
this.tail.next = node;
this.tail = this.tail.next;
}
this.length++;
return this;
}
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 = node;
}
this.length++;
return this;
}
insertNode(value, index) {
if(index >= this.length) {
return this.append(value);
}else if(index <= 0) {
return this.prepend(value);
}else {
const node = this.newNode(value);
const prevNode = this.traversal(index-1);
const nextNode = prevNode.next;
prevNode.next = node;
node.next = nextNode;
this.length++;
return this;
}
}
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 {
this.head = this.head.next;
this.length--;
}
}else {
const prevNode = this.traversal(index-1);
const nextNode = prevNode.next;
prevNode.next = nextNode.next;
nextNode.next = null;
this.length--;
if(nextNode === this.tail) {
this.tail = prevNode;
}
}
return true;
}
}
reverse() {
if(this.length <= 1) {
return this;
}
let prevNode = null, curNode = this.head;
while(curNode !== null) {
const temp = curNode.next;
curNode.next = prevNode;
prevNode = curNode;
curNode = temp;
}
this.tail = this.head;
this.head = prevNode;
return this;
}
traversal(index) {
let current = this.head;
for(let i=0;i < index && current !== null;i++) {
current = current.next;
}
return current;
}
}
class Queues {
constructor() {
this.data = new MyLinkedList();
}
enque(value) {
return this.data.append(value);
}
dequeue() {
const val = this.data.head ? this.data.head.value : null;
if(typeof val !== "undefined") {
this.data.deleteNode(0);
}
return val;
}
peak() {
return this.data.head ? this.data.head.value : null;
}
}
