class Node {
constructor(val, next=null) {
this.val = val;
this.next = next;
}
}
class Queue {
constructor() {
this.first = null;
this.last = null;
this.length = 0;
}
// O(1)
peek(){
if(this.length === 0) return null;
return this.first.val;
}
// O(1)
enqueue(val) {
const newNode = new Node(val);
if(this.length === 0) {
this.first = newNode;
this.last = newNode;
}else{
this.last.next = newNode;
this.last = newNode;
}
this.length++;
return this;
}
// O(1)
dequeue() {
if(this.first === null) return null;
this.first = this.first.next;
this.length--;
return this;
}
}
const myQueue = new Queue();
myQueue.enqueue('Kholid');
myQueue.enqueue('Idris');
myQueue.enqueue('Davud');
myQueue.dequeue();
myQueue.dequeue();
myQueue.dequeue();
console.log(myQueue.peek());
// FIFO
// Enqueue dequeue/peek
// Davud --> Idris --> Kholid -----> School
//
//
