Queue data structure

Queue data structure

• 1.
  QUEUE Anoop joseph Free Powerpoint Templates Page 1
• 2.
  Queue • Ordered collectionof homogeneous elements • Non-primitive linear data structure. • A new element is added at one end called rear end and the existing elements are deleted from the other end called front end. • This mechanism is called First-In-First-Out (FIFO). • Total no of elements in queue= rear – front +1 Free Powerpoint Templates Page 2
• 3.
  Fig: Models ofa Queue Free Powerpoint Templates Page 3
• 4.
  Operations On AQueue 1.To insert an element in queue 2.Delete an element from queue Free Powerpoint Templates Page 4
• 5.
  The Queue Operation Placingan item in a queue is called “insertion or enqueue”, which is done at the end of the queue called “rear”. Front Rear Free Powerpoint Templates Page 5
• 6.
  The Queue Operation Removing an item from a queue is called “deletion or dequeue”, which is done at the other end of the queue called “front”. Front Rear Free Powerpoint Templates Page 6
• 7.
  Algorithm QINSERT (ITEM) 1.If(rear = maxsize-1 ) print (“queue overflow”) and return 2.Else rear = rear + 1 Queue [rear] = item Free Powerpoint Templates Page 7
• 8.
  Algorithm QDELETE () 1.If(front =rear) print “queue empty” and return 2. Else Front = front + 1 item = queue [front]; Return item Free Powerpoint Templates Page 8
• 9.
  Queue Applications  Reallife examples Waiting in line Waiting on hold for tech support  Applications related to Computer Science Round robin scheduling Job scheduling (FIFO Scheduling) Key board buffer Free Powerpoint Templates Page 9
• 10.
  3 states ofthe queue 1.Queue is empty FRONT=REAR 2.Queue is full REAR=N 3.Queue contains element >=1 FRONT<REAR NO. OF ELEMENT=REAR-FRONT+1 Free Powerpoint Templates Page 10
• 11.
  Representation Of Queues 1.Using an array 2.Using linked list Free Powerpoint Templates Page 11
• 12.
  Free Powerpoint Templates Page 12