1. S KIRAN PGT(COMP) KV CLRI
QUEUES
12/12/2019
S KIRAN PGT(COMP) KV CLRI

2. S KIRAN PGT(COMP) KV CLRI
QUEUE
What is a Queue?
A Queue is a linear structure which follows a particular order in which the operations are performed. The order is First In First Out (FIFO) .
12/12/2019
S KIRAN PGT(COMP) KV CLRI

3. S KIRAN PGT(COMP) KV CLRI
REAL LIFE EXAMPLES
Railway ticket counter
Cinema ticket counter
Application form counters
Electricity bill payment counters
12/12/2019
S KIRAN PGT(COMP) KV CLRI

4. S KIRAN PGT(COMP) KV CLRI
APPLICATIONS OF QUEUE
When a resource is shared among multiple consumers. Examples include 1.CPU scheduling 2. Printing (shared resource)
12/12/2019
S KIRAN PGT(COMP) KV CLRI

5. S KIRAN PGT(COMP) KV CLRI
OPERATIONS ON QUEUE
INSERT, the process of adding an element to the queue. If the queue is full, then it is said to be an Overflow condition.
12/12/2019
S KIRAN PGT(COMP) KV CLRI

6. S KIRAN PGT(COMP) KV CLRI
INSERT OPERATION
Rear
Rear
Rear
Rear
Rear
front
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S KIRAN PGT(COMP) KV CLRI

7. S KIRAN PGT(COMP) KV CLRI
OPERATIONS ON QUEUE
DELETE, the process of removing the first element that was added. If the queue is empty, then it is said to be an Underflow condition.
12/12/2019
S KIRAN PGT(COMP) KV CLRI

8. S KIRAN PGT(COMP) KV CLRI
DELETE OPERATION
Rear
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S KIRAN PGT(COMP) KV CLRI

9. S KIRAN PGT(COMP) KV CLRI
IMPLEMENATION
QUEUE can be implemented in two ways 1. STATIC (Arrays) 2. DYNAMIC (Linked List)
12/12/2019
S KIRAN PGT(COMP) KV CLRI

10. Testing Previous Knowledge
What is self referential structure?
It is a structure definition which includes at least one member that is a pointer to the structure of its own kind.
What is linked list?
 A linked list is a linear collection of data elements, in which linear order is not given by their physical placement in memory. Each pointing to the next node by means of a pointer.
12/12/2019
S KIRAN PGT(COMP) KV CLRI

11. S KIRAN PGT(COMP) KV CLRI
DYNAMIC QUEUES
For Dynamic Implementation we require two pointers, front and rear.
The front points the first NODE of queue and rear points to last NODE.
12/12/2019
S KIRAN PGT(COMP) KV CLRI

12. DYNAMIC QUEUE(INSERT)
class QUEUE { Node *rear,*front; public: queue() rear=NULL; front=NULL; } void INSERT(); void DELET(); };
struct Node {
int age;
Node *Link; };
12/12/2019
S KIRAN PGT(COMP) KV CLRI

13. S KIRAN PGT(COMP) KV CLRI
void queue::INSERT() {
Node *nptr = new Node;
if(!nptr)
cout<<“ Over Flow”;
return; }
cout<<"Enter the age ";
cin>>nptr->age;
nptr->Link=NULL;
if(rear==NULL)
front=rear=nptr;
else
rear->Link=nptr;
rear=nptr;
front
NULL
rear
NULL
nptr
1000
1000
1000
2000 F
NULL
1000 R R 23
2000 23
NULL 30
NULL
1000
2000
12/12/2019
S KIRAN PGT(COMP) KV CLRI

14. DYNAMIC QUEUE (DELETE)
front
1000
rear
2000
ptr
1000
void queue::DELET() {
node *ptr = front;
if(front==NULL) cout<<"Underflow";
else
front=front->Link;
delete ptr;
if(front==NULL)
rear=NULL; }
2000
NULL
NULL
2000
1000
2000
NULL R 23
2000
1000 30
NULL
2000
12/12/2019
S KIRAN PGT(COMP) KV CLRI

15. S KIRAN PGT(COMP) KV CLRI
BOARD EVALUATION
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S KIRAN PGT(COMP) KV CLRI

16. S KIRAN PGT(COMP) KV CLRI
void queue::INSERT() {
Node *nptr = new Node; // 1 MARK
if(!nptr)
cout<<“ Over Flow”;
return; }
cout<<"Enter the age ";
cin>>nptr->age; // 1 MARK
nptr->Link=NULL;
if(rear==NULL) // ½ MARK
front=rear=nptr; // ½ MARK
else
rear->Link=nptr; // ½ MARK
rear=nptr; // ½ MARK
12/12/2019
S KIRAN PGT(COMP) KV CLRI

17. S KIRAN PGT(COMP) KV CLRI
THANK YOU
12/12/2019
S KIRAN PGT(COMP) KV CLRI