This document discusses queues, which are linear data structures that follow a first-in, first-out (FIFO) principle. Elements are added to the rear of the queue and removed from the front. Circular queues are also covered, which connect the rear and front to address limitations of linear queues. Real-world applications of queues include lines at stores, waiting on hold, escalators, and bookstore checkouts. Algorithms for enqueue and dequeue operations on both linear and circular queues are provided.

2. Introduction.
Operations on Queue.
Array representation of Queue.
Type of Queue
Circular Queue.
Applications of Queue.

3. A data structure is a particular way of
organizing data in a computer so that it can
be used efficiently.
Different kind of data structure suits for
the different kind of applications.

4. DATA STRUCTURE
PRIMITIVE DS NON-PRIMITIVE DS
Integers
Character
Float
Linear DS Non-Linear DS
 Tree
 Graph
 Array
 Linked list
 Queue
 Stack

5.  Queue is a linear data structure.
 It is used for temporary storage of data values.
 A new element is added at one end called rear
end.
 The existing elements deleted from the other end
called front end.
 First-in-First-out property.
45 25 10 52 78 94 20
front
rear

6. 1.Insertion :
Placing an item in a queue is called “insertion
or enqueue”, which is done at the end of the
queue called “rear”.

7. 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”.

8. 12 9 7 18 5
A[0] A[1] A[2] A[3] A[5] A[6]
Queue
rearfront
12 9 7 18 5 14
9 7 18 5 14
Queue after insertion of new element rearfront
Queue after deletion of an element
rearfront

9. Algorithm:- enqueue
Input:-queue[Max],FRONT,REAR,VALUE
Output:-queue of elements
Begin:-
STEP:1- IF REAR= MAX-1
Print “Queue is OVERFLOW”
Return.
STEP:2- If (FRONT=-1)
FRONT=FRONT+1
STEP:3- REAR = REAR+1
queue[REAR] = VALUE
STEP:4- END.
INITIALLY
REAR = -1
FRONT =-1

10. Algorithm:- de_queue
Input:- queue[MAX],REAR,FRONT
Output:-deleted data ITEM
Begin:-
Step:1-If (REAR=-1)
Print “Queue is UNDERFLOW”
Return.
Step:2-ITEM=queue[FRONT]
Step:3-If (REAR=FRONT)
{
REAR=FRONT=-1
}
Else
FRONT=FRONT+1
Step:4- print deleted data ITEM
END.

11. Circular Queue
INTRODUCTION
 Circular queue are used to remove
the drawback of LINEAR queue.
 Last element of the queue is
connected back with first element of
the queue.
 It is also called as “Ring buffer”.

12. STEP-1 If FRONT = (REAR+1)%MAX
write OVERFLOW
go to step 4
STEP-2 If (REAR=FRONT = -1)
{
REAR = FRONT = +1
}
Else
REAR = (REAR +1)%MAX
STEP-3 CQ[REAR] = NUM
STEP-4 EXIT

13. STEP-1 If FRONT = -1
write UNDERFLOW
go to step 3
STEP-2 ITEM =c_queue[FRONT]
STEP-3 If (FRONT = REAR)
{
FRONT = REAR= -1
}
Else{
FRONT = (FRONT +1)%MAX
}
STEP-3 EXIT

14.  Real world applications
 Cashier line in any store.
 Waiting on hold for tech support.
 people on an escalator.
 Checkout at any book store.

15. “TO MAKE AN END IS TO
MAKE A beginning”.
END OF PRESENTATION
 Thank you for your kind attention.