# What Is Queue and Types of Queue in Data Structure?

//

Scott Campbell

A queue is a data structure that follows the FIFO (First-In-First-Out) principle. It can be visualized as a line of people waiting for a service, where the person who arrives first gets served first. In computer science, a queue is used to store and manage elements in a sequential order.

## Types of Queues

### 1. Simple Queue

A simple queue is the most basic type of queue, where elements are inserted at one end (rear) and removed from the other end (front). It follows the FIFO principle, ensuring that the element that has been in the queue for the longest time gets dequeued first.

### 2. Circular Queue

A circular queue is an improvement over the simple queue, where the last element points back to the first element. This allows efficient utilization of memory space by reusing empty spaces created after dequeuing elements from the front.

#### Operations on Circular Queue:

• Enqueue: Adds an element to the rear of the circular queue.
• Dequeue: Removes an element from the front of the circular queue.
• Front: Returns the element at the front without removing it.
• Rear: Returns the element at the rear without removing it.

### 3. Priority Queue

A priority queue assigns a priority value to each element and dequeues them based on their priority. Elements with higher priority are dequeued before elements with lower priority, regardless of their arrival time.

#### Operations on Priority Queue:

• Enqueue: Adds an element to the priority queue with its associated priority.
• Dequeue: Removes the element with the highest priority from the priority queue.
• Peek: Returns the element with the highest priority without removing it.

### 4. Double Ended Queue (Deque)

A double-ended queue, or deque, allows insertion and removal of elements from both ends. It can be visualized as a combination of a stack and a queue, providing flexibility in managing elements at both ends.

#### Operations on Deque:

• EnqueueFront: Adds an element to the front of the deque.
• EnqueueRear: Adds an element to the rear of the deque.
• DequeueFront: Removes an element from the front of the deque.
• DequeueRear: Removes an element from the rear of the deque.

In conclusion, queues are fundamental data structures used in various computer science applications. Each type of queue has its own characteristics and usage scenarios. Understanding these types will help you choose the appropriate queue for your specific requirements while programming.

I hope this article has provided you with a comprehensive understanding of queues and their types in data structure!