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) {
const newNode = new Node(value);
if (this.isEmpty()) {
this.first = newNode;
this.last = newNode;
} else {
this.last.next = newNode;
this.last = newNode;
}
this.length++;
return this;
}
dequeue(){
if(this.isEmpty()) return null;
if(this.first === this.last) this.last = null;
const removedNode = this.first;
this.first = this.first.next;
this.length--;
return removedNode;
}
isEmpty(){
return this.length === 0;
}
}
