Queue
Unlike stack, a queue works on First in First Out(FIFO) principle. Two main operations are done on a queue; enqueue and dequeue.
To enqueue involves adding item to the back of queue while to dequeue involves removing front item in queue.
Linkedlist as storage
Implementing a queue using linkedlist;
1.The head of list is the head(front) of queue
2.The insertLast method is used to enqueue
3.The removeFirst method is used to dequeue
Implemetation
1.Create node and queue class
class Node { constructor(data, next = null) { this.data = data; this.next = next; } } class Queue { constructor() { this.head = null; this.tail = null; } //add methods } Our queue has a head(front) and tail(back) item.
2.Add methods to our queue class to perform enqueue, dequeue and peek
Enqueue
//add item to queue enqueue(data) { let node = new Node(data); //if empty, set new node as head and tail if (this.tail == null) { this.head = node; this.tail = node; return; } //add node as last item in queue this.tail.next = node; //set node as tail this.tail = node; } Dequeue
//remove item from queue dequeue() { //if empty, do nothing if (this.head == null) { return; } //remove curent head and set head to next item in queue this.head = this.head.next; // set tail to null if queue is emptied if (this.head == null) { this.tail = null; } } peek
//return first item in queue peek() { if (this.head == null) { return "Queue is empty"; } return this.head.data; } I'll be implementing a queue with arrays next, stay tuned.
Happy Coding! 👯
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