1. STACKS & QUEUES
for CLASS XII ( C++)

2. STACKS
AND
QUEUES

3. Objective Introduction to Data Structure Array and Link list Stack
Array implementation of Stack
Linked Implementation of Stack
Queue
Array implementation of Queue
Linked Implementation of Queue

4. DATA STRUCTURE: INTRODUCTION
A mathematical and logical model of data is known as Data Structure.   Primitive data structure: The data structure, which is available in the compiler, is known as a primitive data structure. Non-primitive data structure: The data structure, which is not available in the compiler, is known as non-primitive data structure.  

5. DATA STRUCTURE: INTRODUCTION
  Linear Data Structure: The data structure in which each element has access to maximum of one predecessor element and maximum of one successor element is known as linear data structure. Example: Stack, Queue, etc. Non-linear Data Structure: The data structure in which each element can access any number of predecessor elements and any number of successor elements is known as Non-linear data structure. Example: Tree, Graphs, etc.  

6. TYPES OF DATA STRUCTURE
Static Data Structure: The data structure in which the number of elements is fixed, is known as Static Data Structure. Example: Arrays Dynamic Data Structure: The data structure in which the number of elements is not fixed, is known as Dynamic Data Structure. Example: Linked List.

7. ARRAY
It is a static data structure. It is a homogeneous collection of data. The elements in the array are stored on consecutive memory locations. Array is also known as a subscripted variable, e.g., A[i] is ith element of the array A.

8. STACK
It is a non-primitive linear data structure in which insertion and deletion of elements takes place from only one end, known as top.
QUEUE
It is a non-primitive linear data structure in which insertion and deletion of elements takes place from two opposite ends rear and front respectively.

9. STACKS
Stacks is LIFO (Last In First Out) structure and physically can be implemented as an array or as a linked list.
Stack, when implemented as an array is functionally same as any other array except that here, adding an element and deletion is done from the same direction just like a pile of books.

10. Implementation of STACK in computers
Inserting an element in an array is known as PUSH.
Deleting an element from an array is known as POP.
Implementation of STACK in computers
When functions are called.
To convert a infix expression to postfix.
To evaluate a postfix expression.

11. Representation of STACK
A stack is a list in which insertion and deletion takes place only at one end called top. Thus, called LIFO.
Representation of STACK
data1
data2
data3
data4
TOP
TOP
data4
data3
data2
data1
data1
data2
data3
data4
TOP
TOP
data4
data3
data2
data1
Each one of the above has one open and one close end and data movement takes place from open end.

12. Basic operation and implementation of stacks
Creation of stack
Check for empty stack
Check for full stack
Add element in stack
Delete element in stack
Print stack

13. STACKS
The fundamental operations that can be performed on stack are PUSH and POP.
When element is added on the stack top is called PUSH.
And When Data is removed from the stack top, the operation is called POP.

14. STACK The stack operation can be explained as follows:
Stack operation Content of array
Push(a) a
Push (a) a
Push(b) ba
Push(b) b a
Push( c) cba
Pop() ba
Push( c) C b a
Pop() a
Pop( c) b a
Pop(b) a

15. STACKS
A stack is a list, any list implementation can be used to implement stack.
We can implement stack by the following data structures:
Array called Linear Stack
Linked List called Linked Stack

16. Linear Stack Stack array int TOP; int S[5];
To hold address of location where data is inserted or deleted
int TOP;
When PUSH is selected, TOP is incremented,
And data is added at that subscript location
When POP is selected, TOP is decremented,
And data is removed from that subscript location

17. Lets see working of Linear Stack8 9 10 7 8 9 10 20 7 8 9 10
TOP
TOP
OVERFLOW
ARRAY IS FULL
TOP
Push 7
Push 20
Push 14
Top is incremented
TOP++

18. CONTINUED…. 20 7 8 9 10 7 8 9 10
TOP 8 9 10
Top
UNDERFLOW OCCURS WHEN STACK IS EMPTY
Top
Pop 20
TOP is decremented
TOP --
Pop 7

19. Lets see this using a program
Click here to execute program
Program Code for the Same is
Click here to see program code

20. POINTER Pointer P holds address of amt
A variable which holds an address of a memory location of another variable is known as a Pointer Variable (or only pointer). Example int amt, *p;
Requires 2 bytes
900
amt
0x8ffebab4
Requires 2 bytes
0x8ffebab4 *P
Pointer P holds address of amt

21. DYNAMIC ALLOCATION
NEW operator in C++ returns the address of a block of unallocated bytes (depending on data type a pointer pointing to). DELETE operator in C++ reverses the process of new operator, by releasing the memory location from a pointer. It de allocates memory assigned by NEW.

22. LINK LIST To allocate dynamic allocation and store address in point g
A pointer, which stores the address of struct type data, is known as Pointer to structure.
struct abc {
int X,Y; };
struct *g=new abc;
Holds address of dynamic object of struct abc
To allocate dynamic allocation
and
store address in point g G
0x8ff134ab
G->X
G->X
G->Y
0x8ff134ab

23. LINK STACK To hold address of First node of the list
struct STACK // structure for stack {
int data;
STACK *link; };
struct *TOP;
To hold address of
First node of the list
TOP pointer to holds address of dynamic objects of link stack.
As we push a node TOP element get shifted and new node becomes first node.
LIFO implementation every new node becomes first node.
When we pop Top node is deleted and next node becomes first node.

24. Lets see working of Linked stack
Push operation
Lets see working of Linked stack
Temp holds address of new location
* TOP
* Temp
NULL
Initially top is assigned NULL
0x8ffab2e6
A new memory is allocated and address is stored in temp
Top = Temp
Top will hold address of new location
data link
* TOP
X NULL
0x8ffab2e6
0x8ffab2e6
Thus, TOP will have this address.

25. Cont….. *TOP Another new memory is allocated to an object 0x8ffab2e6
* Temp
0x8ffab2e8
TOP will get shifted
Y becomes first node
X becomes second node
temp-> link = Top
Top=temp
* TOP
0x8ffab2e8
data link
Now TOP is Y
0x8ffab2e6
data link
0x8ffab2e8
X NULL
0x8ffab2e6

26. An object is deleted from top delete temp (to release memory)
POP operation
Cont…..
An object is deleted from top
* TOP
* Temp
TOP will get shifted
X becomes first node
Y will be released
0x8ffab2e8
0x8ffab2e8
Temp=TOP
TOP=TOP->link
Thus Top will be
* TOP
delete temp (to release memory)
0x8ffab2e6
data link Y
0x8ffab2e6
data link
0x8ffab2e8
X NULL
0x8ffab2e6

27. Program Code for the Same is
Lets see this using a program
Click here to execute program
Program Code for the Same is
Click here to see program code

28. Queues
Queue is FIFO (First In First Out) structure and physically can be implemented as an array or as a linked list.
Queue, when implemented as an array is functionally same as any other array except that here, adding an element and deletion is done from the one direction and deletion from other just like any queue of peoples.

29. Implementation of queue in computers
Queues
Inserting an element in an array is known as insert.
Deleting an element from an array is known as delete
But this is done with the help of two parameters rear and front.
Implementation of queue in computers
When program is executed.

30. Representation of Queue
A Queue is a data structure in which insertion is done at the end and deletion is done from the front of queue. It is FIFO .
Representation of Queue
Rear
data2
data3
data4
data4
data3
data2
Front
data2
data3
data4
Front
Rear
data4
data3
data2
Rear
Front
Each one of the above has two open end Front and Rear. Insertion is done from Rear and deletion form Front
Front
Rear

31. Basic operation and implementation of QUEUE
Creation of Queue
Check for empty Queue
Check for full Queue
Add element in Queue
Delete element in Queue
Print Queue

32. QUEUE
The fundamental operations that can be performed on Queue are Insert and Delete.
When element is added on the Queue Front is called Insert.
And When Data is removed from the Queue Rear, the operation is called Delete.

33. Though first two cells are empty
QUEUE
The Queue operation can be explained as follows:
Queue operation Content of array
Insert(a) Front=0 Rear=0 a
Insert(b) Front=0 Rear=1
Insert( c) Front=0 Rear=2 a b
Delete() Front=1 Rear=2
Delete() Front=2 Rear=2 a b c
If we try to insert
Overflow occurs
Though first two cells are empty b c c

34. Linear Queue Queue array int Front, Rear; int Q[5];
To hold address of location where data is inserted or deleted
int Front, Rear;
When INSERT is selected, Rear is incremented,
And data is added at that subscript location
When DELETE is selected, Front is decremented,
And data is removed from that subscript location

35. QUEUE
A Queue is a list, any list implementation can be used to implement Queue.
We can implement Queue by the following data structures:
Array called Linear Queue
Linked List called Linked Queue

36. Lets see working of LINEAR QUEUE8 9 10 7 8 9 10 20 7 8 9 10
rear
rear
OVERFLOW
QUEUE is full
rear
Front
Front
Front
Insert 20
Insert 7
Insert 14
Rear is incremented
Rear++

37. Lets see working of Queue as an array20 7 8 9 10
Rear 20 7 8 9
Rear 20 7 8
Rear
Underflow occurs when QUEUE is empty
Front
Front
Front
Delete
Delete
Front is incremented
Front++

38. Lets see this using a program
Click here to execute program
Program Code for the Same is
Click here to see program code

39. First and Last node of the list
LINKED QUEUE
struct QUEUE // structure for QUEU {
int data;
QUEUE *link; };
struct *Front,*Rear;
To hold address of
First and Last node of the list
Front and Rear pointer to holds address of dynamic objects of link stack.
As we insert a node Rear element get shifted and new node becomes next node.
FIFO implementation every new node added at end.
When we Delete Front node is deleted and next node becomes first node.

40. Lets see working of Linked Queue
Insert operation
Lets see working of Linked Queue
Temp holds address of new location
* Front * Rear
* Temp
NULL NULL
Initially Front and Rear is assigned NULL
0x8ffab2e6
A new memory is allocated and address is stored in temp
Front=Rear = Temp
Front and Rear will hold address of First location
data link
* Front * Rear
X NULL
0x8ffab2e6 0x8ffab2e6
0x8ffab2e6
Thus, Front and Rear will have this address.

41. Cont….. Another new memory is allocated to an object *Front * Rear
0x8ffab2e6 0x8ffab2e6
* Temp
0x8ffab2e8
Rear will get shifted
Y becomes Last node
temp-> link = Rear
Rear=temp
* Rear
0x8ffab2e8
data link
Now Rear is X
0x8ffab2e8
data link
0x8ffab2e6
Y NULL
0x8ffab2e8

42. An object is deleted from Front delete temp (to release memory)
Delete operation
Cont…..
An object is deleted from Front
* Front * Rear
* Temp
0x8ffab2e6 0x8ffab2e8
0x8ffab2e6
Front will get shifted
Y becomes first node
X will be released
Temp=Front
Front=Front->link
Thus Front will be
* Front
delete temp (to release memory)
0x8ffab2e8
data link X
0x8ffab2e8
data link
0x8ffab2e6
Y NULL
0x8ffab2e8

43. Program Code for the Same is
Lets see this using a program
Click here to execute program
Program Code for the Same is
Click here to see program code

44. CIRCULAR QUEUE
The fundamental operations that can be performed on Circular Queue are Insert and Delete.
When overflow occurs though the free cells are available, Rear reaches ends Circular Queue is implemented to avoid this drawback.
In Circular Queue as soon as Rear reaches maximum it should reset to 0.

45. QUEUE The Queue operation can be explained as follows:
Queue operation Content of array
Insert(a) Front=0 Rear=0 a
Insert(b) Front=0 Rear=1
Insert( c) Front=0 Rear=2 a b
Delete() Front=1 Rear=2
Insert (d) Front=2 Rear=0 a b c
Overflow occurs only when
Array is FULL.
Rear moves to 0 if array is empty b c d c

46. Program Code for the Same is
Lets see this using a program
Click here to execute program
Program Code for the Same is
Click here to see program code

47. Do you have any ?
QUESTIONS

48. TEST YOUR KNOWLEDGE What is difference between Stack & Queue?
What is Dynamic Allocation?
What is the significance of Top?
What is the significance of Front & Rear?
What is Overflow?
What is Underflow?
Where Stack is Implemented?

49. THANK
YOU