Stack and queue power point presentation data structure and algorithms Stack-Queue-LL.pptx

Introduction and Overview
of Data Structure
• This part will introduce the concept of data structure. But before the discussion of data
structure we will have a look of some elementary concepts and terminology related to data
structure.
• Data
• “A well-known fact that has some implicit meaning and that can be recorded is known as
data”.
In simplest words we can say that data means value or set of values. So raw facts and figures
about any thing may be termed as data. Some of the examples are
Robert
34
New Jersey
07-04-1980
CEO
• In the above example we are having some figures but these figures are not able to represent
the clear message. Means we don’t know what is the meaning of this data.

• Information
• Processed data is known as information.
• Means after processing of data we can get clear message inherited into the data or
meaningful data is called information
• In other words “data +associated attributes” may be termed as information
• The above example can be represented in such a way
Employee Name -- Robert
Age -- 34
City -- New Jersey
Date of Joining -- 07-04-1980
Designation -- CEO
• This example gives the information that Robert, which is a 34 year old, lives in New Jersey. He
is CEO in a company and his date of joining is 07-04-1980
• Relation between data and information
DATA
Procedure
to process
the Data
Information

Data Structure
• Data structure is the structural representation of logical relationship between elements of
data. Or in other words a data structure is a way of organizing data items by considering its
relationship to each other.
• ALGORITHMS + DATA STRUCTURE = PROGRAM
• Data structures are the building blocks of a program. Means the selection of a poor data
structure may design an inefficient program.
LIBRARY
• Classification of fundamental Data Structure-
• Some of the data structures are used frequently almost in all application areas and with the
help of which almost all-complex data structure can be constructed. These data structures
are known as fundamental or classic data structure. Classification of all fundamental data
structures is as follows:

Classification of Data Structure
Fundamental data Structure
Linear Data Structure
Non-Linear Data Structure
Arrays Stacks Queues Linked List Trees Graphs Tables Sets

Data Structure Operations
• Traversing-Accessing each record exactly once.
• Searching-Finding the location of the record with the given key value.
• Inserting-Adding a new record to the structure.
• Deleting-Removing a record from the structure
• Sorting-Arranging the records in some logical order.
• Merging-Combining the records

Arrays
• An array is a finite, ordered collection of homogeneous data elements. Array is finite because
it contains only limited number of elements, and ordered, as all the elements are stored one
by one in contiguous locations of computer memory in a linear ordered manner. All the
elements of an array are of the same data type that is why termed as collection of
homogeneous elements.
• Array may be one-dimensional or multidimensional. In multidimensional array elements are
arrange in the form of row and column. Elements of an array can be accessed through index
(say i) or subscript.
• If we want to store n elements in an array A then the elements will store from A[0] to A[n-1].
Any particular element can be represented as A [i]. The diagrammatic representation would
be as follows-
A[0] A[1] A[2] ………… A[n-1]

• “A stack is an ordered collection of homogeneous data element where the insertion and
deletion operations take place at one end only called TOP of the stack”
• In case of arrays and linked list, insertion and deletion operations can take place at any
position. But in case of stack insertion and deletion operations are known as PUSH and POP
and restricted to one end only, known as TOP of the stack. An element in a stack is termed as
ITEM. The maximum number of elements that a stack can accommodate is termed its size.
The last inserted element in stack, will be first removed from the stack. That is why the stack
is known as LAST IN FIRST OUT (LIFO).
Insert Elements(PUSH) Delete last inserted element(POP)
Top of the Stack
Bottom of the Stack
ITEM 1
ITEM 2
ITEM 3
ITEM 4
ITEM 5

Operations on Stack
PUSH
The process of adding a new element to the top of stack is called PUSH. Pushing an element
in the stack involve adding new element In case the array is full and no new element can be
accommodated, it is called the STACK OVERFLOW.
POP
The process of deleting an element from the top of stack is called POP. After every pop
operation the stack is decremented by one. If there is no element in the stack and POP is
performed then this will result into STACK UNDERFLOW.
Implementation of Stack
Stack can be implemented in two ways
Stack implementation using arrays (static implementation)
Stack implementation using pointers (dynamic implementation)

ALGORITHM
TOP-top of stack. Initial value of TOP is 0
ITEM- element to be inserted
MAXSTK- maximum size of stack
PUSH ( STACK ,TOP ,ITEM ,MAXSTK )
This procedure pushes an item onto stack.
If TOP = MAXSTK , then : Print: OVERFLOW, and Return.
Set TOP = TOP+1
Set STACK [TOP] = ITEM
Return.
POP ( STACK ,TOP ,ITEM )
If TOP = 0 , then : Print : Underflow, and Return.
Set ITEM = STACK [TOP]
Set TOP = TOP- 1
Return.

Applications of Stacks
– Page-visited history in a Web browser
– Undo sequence in a text editor
– Backtracking
– Saving local variables when one function calls another, and
this one calls another, and so on.
– Recursion
– Infix to postfix conversion
– Quick sort
– Mobile

Queues
• A Queue is an ordered collection of items from which items may be deleted at one end
(called the front of the queue) and into which items may be inserted at the other end (the
rear of the queue).
• The first element inserted into the queue is the first element to be removed. For this reason
a queue is sometimes called a fifo (first-in first-out) list as opposed to the stack, which is a lifo
(last-in first-out).

QUEUE OPERATIONS
• Initialize the queue
• Insert to the rear of the queue
• Remove (Delete) from the front of the queue
• Is the Queue Empty
• Is the Queue Full
• What is the size of the Queue
• Implementation of Queue
Queue can be implemented in two ways
Queue implementation using arrays (static implementation)
Queue implementation using pointers (dynamic implementation)

Queue Implementation using Circular Array
QINSERT(QUEUE,N,FRONT,REAR,ITEM)
1. [Queue already filled?]
If FRONT=1 and REAR=N or if FRONT=REAR+1 then
Write OVERFLOW and exit.
2. If FRONT=NULL then[Queue is initially empty]
Set FRONT=1 and REAR=1
Else if REAR=N then set REAR=1
Else set REAR=REAR+1
3. Set QUEUE[REAR]=ITEM
4 . Exit
QDELETE(QUEUE,N,FRONT,REAR,ITEM)
1. [Queue already empty]
If FRONT=NULL then Write UNDERFLOW and exit.
2. Set ITEM=QUEUE[FRONT]
3. If FRONT=REAR then [queue has only one element to start]
Set FRONT=REAR=NULL
Else if FRONT=N then Set FRONT=1
else Set FRONT=FRONT+1
4. Exit

Types and Applications of Queue
TYPES
• Deque or Dequeue (Input Restricted/Output Restricted)
• Priority Queue
Applications
• Waiting lines
• Access to shared resources (e.g., printer)
• printer queue, keystroke queue, etc.
• Searching(DFS & BFS)
• Used extensively in operating systems
• Multiprogramming
• Queues of processes, I/O requests, and much more

Linked List
• Array is a data structure where elements are stored in consecutive memory locations. We
have to specify the size of array before its usage. Once memory is allocated it cannot be
extended any more. That is why array is known as static data structure.
• In contrast to this linked list is called dynamic data structure where amount of memory
required can be varied during its use. A linked list consists of nodes.
• A node consists of two fields; one is data (actual content) and link (which point to the next
data).
LINK
Link to the Next Node
Node: An element in a linked list
DATA

Definition
• A linked list or one way list is an ordered collection of finite data elements called nodes where
the linear order is maintained by means of links or pointers.
DATA LINK DATA LINK DATA LINK
Linked List representation
START
22 40 50 NULL

TO CREATE LINK LIST
In C, a linked list is created using structures, pointers and dynamic memory allocation
function .We consider head as an external pointer. This helps in creating and accessing other
nodes in the linked list. Consider the following structure definition and head creation:
Struct node
{
int DATA;
struct node *ptr;
};
typedef struct node NODE;
NODE *start;
Start=(NODE *)malloc(sizeof(NODE));
When the Statement
Start=(NODE *)malloc(sizeof(NODE));
Is executed , a block of memory sufficient to store the NODE is allocated and assigns head as
the starting address of the NODE. This activity can be pictorially shown as follows:-
start DATA ptr

Types of Linked List
• Header Linked List
-Grounded Header Linked List
-Circular Header Linked List
• Two way Linked List
• Two way Circular Header Linked List
Applications of linked List
• Dynamic Memory Allocation
• Polynomials representations and various operations over polynomials
• Non Contiguous Memory Allocation
• Representing Sparse Matrix
• Representation of PCB in Operating system

Inserting After a Given Node
• Suppose we are given the value of LOC where
either LOC is the location of a node A in a linked list
or LOC=NULL, so that ITEM is the first node.

Deleting the node Following a Given Node
Let LIST be a linked list in memory. Suppose we are given the
location LOC of a node N in LIST. Furthermore we are given
the location LOCP of the node preceding N or. when N is the
first node, we are given LOCP=NULL.

HEADER LINKED LISTS
A header linked list is a linked list which always
contains a special node, called the header node
at the beginning of the list. The following are two
kinds of widely used header lists:
• A gronded header list is a header list where the
last node contains the null pointer. (The term
grounded comes from the fact that many texts
use the electrical ground symbol to indicate the
null pointer.)
• A circular header list is a header list where the
last node points back to the header node

Stack and queue power point presentation data structure and algorithms Stack-Queue-LL.pptx

TWO WAY LISTS (OR DOUBLY LINKED LIST)

Linked Implementation of Stack

Linked Implementation of Queue
LINKQ_INSERT(INFO,FRONT,REAR,AVAIL,ITEM)
• 1. If AVAIL = NULL then write OVERFLOW and Exit.
• 2. Set NEW=AVAIL and AVAIL=LINK[AVAIL]
• 3.Set INFO[NEW]=ITEM and LINK[NEW]=NULL
• 4.If FRONT =NULL then FRONT=REAR=NEW
• Else Set LINK[REAR]=NEW and REAR=NEW
• 5. EXIT

LINKQ_DELETE(INFO,LINK,FRONT,REAR,AVAIL,ITEM)
• 1. If FRONT=NULL the write UNDERFLOW and
Exit.
• 2.Set TEMP=FRONT
• 3.ITEM=INFO[TEMP]
• 4.FRONT=LINK[TEMP]
• 5.LINK[TEMP]=AVAIL and AVAIL=TEMP
• 6. Exit

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