Applications of Linked List (Queue)

Applications Of Linked List

Part 2 Queue

Now that we have an understanding of what linked list are and have seen where the singly linked list can be used , lets check the usage of doubly linked list. 

Doubly Linked List:

Doubly Linked List can be used for various applications, one of the application is for modelling finite state machines, each node in doubly linked list can act as a state in finite state machine. Another application is if we want to implement Queue Abstract Data Structure. 

Queue:

Queue is an abstract data structure, Queue is also called as FIFO , as it follows First in first out principle. The item/data/process which entered first in the queue data structure is processed first in queue data structure. Queue supports two basic operations , enqueue and dequeue . 

Enqueue

•  enqueue means to add an element/data/node at the end of the queue. 

Dequeue 

• dequeue means to process the element/data/node which is at the front of the queue and          remove it from the queue

CPP Program for Queue:

	//
	// main.cpp
	// queue
	// Created by Sarvesh Bhatnagar on 05/03/18.
	// Copyright © 2018 introtoalgo.com. All rights reserved.
	//
	#include <iostream>
	using namespace std;
	struct doublyLinkedList{
	int id;
	struct doublyLinkedList *next;
	struct doublyLinkedList *prev;
	};
	struct doublyLinkedList *temp,*first,*last;
	void makeDoublyLinkedList();
	void enQueue();
	void deQueue();
	int main() {
	cout<<"Enter Number of Queue Items you want to insert"<<endl;
	int n;
	cin>>n;
	for (int i = 0; i<n; i++) {
	enQueue();
	}
	cout<<"Enter how many Queue items you want to process? "<<endl;
	cin>>n;
	for (int i = 0; i<n; i++) {
	deQueue();
	}
	return 0;
	}
	void enQueue(){
	temp = new doublyLinkedList();
	temp->prev = NULL;
	temp->next = NULL;
	if (first == NULL) {
	first = temp;
	}
	else{
	last->prev = temp;
	temp->next = last;
	}
	last = temp;
	cout<<"Enter id"<<endl;
	cin>>temp->id;
	}
	void deQueue(){
	temp = first;
	if (first != NULL) {
	cout<<first->id<<endl;
	if (first->prev != NULL) {
	first = first->prev;
	}
	else{
	cout<<"Queue Emptied"<<endl;
	first = NULL;
	}
	free(temp);
	}
	else{
	cout<<"Empty Queue"<<endl;
	}
	}

view raw queue.cpp hosted with ❤ by GitHub

Written By, Sarvesh Bhatnagar

CPP Program For Doubly Linked List

Linked List Part 1