Queue

Queue

• Queue is a linear data structure.
• Like stack, queue is also an ordered list.
• It follows the FCFS or FIFO policy.
• It has one end called the REAR(also called tail) which used to insert new item.
• To removal of existing element called FRONT(also called head).
• The process to add an element into queue is called Enqueue.
• The process of removal of an element from queue is called Dequeue

• FCFS stands for First Come First Serve.
• FIFO stands for First In First Out.
• Example: Queue of Passport Office, ADHAAR Card Office, Traffic Signal Cars
  

• It has mainly two types of operations.
• Insertion: we can insert value from rear or tail direction. 
• Deletion: we can delete or remove value from the front or head direction.
  

• It can represent by two ways:
• Using Array
• Queue is also a collection of same type of elements.
• So, we can take array for implementing the Queue operations.
• Using Linked List
• Queue can be implemented through Linked List.

Operations on Queue:
Insertion

Deletetion

Applications of Queue

• To shared resource, like a printer, CPU task scheduling, etc.
• To use calling phone at PhoneBooth (STD)
• Handling of interrupts in real-time systems.

Types of Queue:

1. Simple Queue

• Queue operations: Insert & Delete

2. Circular Queue

3. Double Ended Queue

4. Priority Queue