The document discusses data structures, specifically comparing simple queues and circular queues. It outlines the operations of both types of queues, detailing the algorithms for inserting and deleting elements, as well as addressing their advantages and disadvantages. The circular queue allows for better memory management by resetting pointers, preventing overflow issues common in simple queues.

1. Data Structure
P. M. Patil

2. 0 1 2 3
Q
0 1 2 3
Q
20
Disadvantage of Simple Queue
40
0 1 2 3
Q
F
R
-1
0 1 2 3
Q Insert(10)
10
F
R
0 1 2 3
Q
Insert(20)
R
10 20
F
0 1 2 3
Q
Insert(30)
R
F
10 20 30
Insert(40)
R
F
10 20 30
40 Delete()
R
F
20 30

3. Disadvantage of Simple Queue
Insert (50)
Now we can not insert a value in Simple Queue
because it is OVERFLOW since R==Size-1
0 1 2 3
Q
R
F
40
20 30

4. Circular Queue
• In CQ we reset the Rear pointer
Operations of CQ
1) Insert
2) Delete

5. Algorithm for Insert CQ
Procedure CQINSER (F,R,CQ,Size) This procedure will insert an element into CQ which is a circular
queue.F and R are the pointers to the front and rear of the queue respectively. Initially F and
R are set to -1. Item is a temporary variable used.
1.[Reset rear pointer]
If R=Size -1
then R<- 0
Else R<- R+1
2. [Check for overflow]
if F=R
then Write(‘Overflow’)
End If
3. [Insert element in CQ]
Read(Item)
CQ[R]<- Item
Write(‘Item is inserted in CQ’)
4. [Set front properly]
If F=-1
then F<- 0
Else

6. 0 1 2 3
CQ
0 1 2 3
CQ
20
Advantage of Circular Queue
40
0 1 2 3
CQ
F
R
-1
0 1 2 3
CQ Insert(10)
10
F
R
0 1 2 3
CQ
Insert(20)
R
10 20
F
0 1 2 3
CQ
Insert(30)
R
F
10 20 30
Insert(40)
R
F
10 20 30
40 Delete()
R
F
20 30

7. Advantage of Circular Queue
Insert (50)
Now we can insert a value in Circular Queue
because R pointer is reset to 0 R=0;
Memory is not wasted in circular queue.
0 1 2 3
Q
R F
50 20 30 40

8. Algorithm for Delete CQ
Procedure CQDELETE (F,R,CQ,Size) This procedure will delete an element from the CQ which is a
circular queue. F and R are the pointers to the front and rear of the queue respectively.
Initially F and R are set to -1. Item is a temporary variable used.
1.[Check CQ underflow]
If F = -1
then Write(‘CQ is underflow’)
Endif
2. [delete element]
Item =CQ[F]
Write(‘Item is deleted’)
End If
3. [Reset R and F]
if F=R
then F-1
R=-1
4. [Increment F]
If F= size-1
then F<- 0
Else
F<-F+1