# Types of Queues

In this tutorial, you will learn various types of queues along with illustrations.

Contents

## What is a queue?

A Queue is a FIFO (First In First Out) data structure where the element that is added first will be erased first. The essential queue tasks are enqueue (insertion) and dequeue (deletion). Enqueue is done at the front of the queue and dequeue is done toward the end of the queue. The elements in a queue are arranged sequentially and thus queues are supposed to be linear data structures.

The practical instances of queues are

• The consumer who comes first to a shop will be served first.
• CPU task scheduling and disk scheduling.
• Waiting list of tickets in case of bus and train tickets.

A queue is a useful data structure in programming. It is like the ticket line outside a cinema hall, where the first individual entering the queue is the first individual who gets the ticket.

There are four unique sorts of queues:

• types of queueSimple Queue
• Circular Queue
• Priority Queue
• Double Ended Queue

## Simple Queue

In a basic queue, insertion happens at the back and evacuation happens at the front. It strictly follows the FIFO (First in First out) rule.

## Circular Queue

In a circular queue, the last element points to the primary element making a circular connection.

The primary advantage of a circular queue over a simple queue is better memory use. On the off chance that the last position is full and the first position is unfilled, we can insert an element t in the first position. This activity is possible in a straightforward queue.

## Priority Queue

A priority queue is a unique sort of queue where each element is related to a priority and is served by its priority. On the off chance that elements with a similar need happen, they are served by their request in the queue.

Insertion happens based on the appearance of the values and removal happens based on priority.

## Deque (Double Ended Queue)

In a double finished queue, insertion and removal of elements can be performed from either from the front or back. In this way, it doesn’t follow the FIFO (First In First Out) rule.

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