Queue
- 1. Queue is an abstract data structure that follows the FIFO (First In First Out) principle where an element that is added first will be deleted first. Also, there are linear data structures as the elements are linearly arranged. QUEUE
- 2. Agner Krarup Erlang (1878-1929) the Danish telecommunication engineer started applying principles of queuing theory in the area of telecommunications.
- 3. QUEUE--
- 4. Operations on Queue--- 1.Insertion : Placing an item in a queue is called “insertion or “enqueue”, which is done at the end of the queue called “rear”. 2.Deletion : Removing an item from a queue is called “deletion or “dequeue” , which is done at the other end of the queue called “front”
- 6. Types of Queues-- 1. Deque 2. Circular Queue 3. Priority Queue
- 7. DEQUES-- 1.Deque stands for double ended queue. 2.Elements can be inserted or deleted at either end. 3. Also known as head-tail linked list.
- 8. TYPE OF DEQUEUE-- Input restricted dequeue Element can be inserted only at one end. Element can be removed by both end. Output restricted dequeuer Element can be inserted at both end. Element can be removed by one end.
- 9. CIRCULAR QUEUES--- • Circular queue are used to remove the drawback of simple queue. • Both the front and the rear pointers wrap around to the beginning of the array. •It is also called as “Ring buffer”
- 10. PRIORITY QUEUE--- 1.It is collection of elements where elements are stored according to the their priority levels. 2.Inserting and removing of elements from queue is decided by the priority of the elements. 3. An element of the higher priority is processed first. 4.Two element of same priority are processed on first-come-first-served basis.
- 11. Example: Suppose you have a few assignment from different subjects.Which assignment will you want to do first? Subject Due date Priority DLD 6 OCT 2020 1 OR 12 OCT 2020 3 DSN 10 OCT 2020 2 DSA 13 OCT 2020 4
- 12. APPLICATIONS-- **Real world applications** Cashier line in any store. Waiting on hold for tech support. people on an escalator. Checkout at any book store Traffic light functioning is the best example for circular queues. The colors in the traffic light follow a circular pattern. In page replacement algorithms, a circular list of pages is maintained and when a page needs to be replaced, the page in the front of the queue will be chosen.
- 13. Real world applications--- Please play this Video
- 15. Applications related to computer science: 1.When data is transferred asynchronously between two processes. eg. IO Buffers. 2.When a resource is shared among multiple consumers. Examples include CPU scheduling, Disk Scheduling. 3.In recognizing palindrome. 4.In shared resources management. 5.Keyboard buffer. 6.Round robin scheduling. 7.Job scheduling. 8.Simulation