class Node {
constructor(value) {
this.value = value;
this.next = null;
}
}
class Queue {
constructor() {
this.first = null;
this.last = null;
this.length = 0;
}
peek() {
return this.first;
}
enqueue(value) {
let node = new Node(value);
// if the queue is empty
if (this.length === 0) {
this.first = node;
this.last = node;
this.length++;
return this;
}
// if the queue is not empty
this.last.next = node;
this.last = node;
this.length++;
return this;
}
dequeue() {
// if the queue is empty
if (this.length === 0) {
return null;
}
// if the queue has only 1 element
if (this.length === 1) {
let val = this.first;
this.first = null;
this.last = null;
this.length--;
return val.value;
}
let val = this.first;
this.first = this.first.next;
this.length--;
return val.value;
}
isEmpty() {
return (this.length === 0);
}
// print the elements in the queue
printList() {
const values = [];
let val = this.first;
while (val !== null) {
values.push(val.value);
val = val.next;
}
console.log(values.join(","));
}
}
const myQueue = new Queue();
// console.log(myQueue.isEmpty());
// console.log(myQueue.dequeue());
myQueue.enqueue(10);
myQueue.enqueue(20);
myQueue.enqueue(30);
myQueue.enqueue(40);
myQueue.printList();
console.log(myQueue.dequeue());
myQueue.printList();
// console.log(myQueue.peek());
// myQueue.printList();
// console.log(myQueue.dequeue());
// myQueue.printList();
// console.log(myQueue.dequeue());
// myQueue.printList();
// console.log(myQueue.isEmpty());
// console.log(myQueue.length);
// console.log(myQueue);
