Presentation and talk on Data Structures and Queues

1. Data Structures: Stack & Queue
01
Mrs. Nimrita Koul
School of Computing & IT
REVA University
Bangalore, India

2. Contents
1. Data & Data Type
2. Data Structures
3. Stack
1. Structure
2. Operations
3. Applications
4. Queue
1. Structure
2. Operations
3. Applications
4. Variants
2

3. 3
DATA  facts and statistics
Characters:
Grades, Labels
etc.
Text: Names,
Address,
Designations
Numbers : Age,
Distance , Height
etc.
Images, Videos
and Songs

4. 4
Data Types
Primitive Types
Derived Types:
Aggregation of Primitive Types

5. 5
DATA
STRUCTURE-
An organization
of data to suit a
specific
Purpose
STACK
TREE
QUEUE
LIST
HEAP
HASH TABLE
It has data and the operations that
can be done on stored data

6. 6
STACK
A LAST IN-FIRST OUT ARRANGEMENT OF DATA ITEMS

7. 7
Stack Features
Homogeneous Data
Members
Variable Length
LAST IN – FIRST OUT
TOP-An access pointer for
insertions and deletions
Stack Operations
PUSH- Insert Element at
Top, (overflow if full)
POP- Delete Element at
Top, (Underflow if empty)
PEEK- Read the Element at
Top
isEmpty- Check if the Stack
is empty
isFull- Check if the Stack is
Full
push(), pop(), isEmpty(), isFull() and peek() all take O(1) time. There is no loop in
any of these operations.

8. Objectives
• 1. To develop an algorithm for feature selection
from gene expression data
• 2. To develop an algorithm for inference of gene
regulatory networks
• 3. To develop an algorithm for classification of
tumor samples based on results of 1 and 2.
8

9. Implementation as an Array
9
void push()
{
if(top>=size-1)
{
printf("ntSTACK FULL");
}
else
{
printf(" Enter a value to
be pushed:");
scanf("%d",&x);
top++;
stack[top]=x;
}
}
void pop()
{
if(top<=-1)
{
printf("nt Stack
EMPTY");
}
else
{
printf("nt The popped
elements is %d",
stack[top]);
top--;
}
}
int size=5;
int stack[size];
int top;

10. Implementation as a Linked List
10
void push(int value)
{
node *tmp;
tmp =
malloc(sizeof(node));
tmp -> data = value;
tmp -> next = top;
top = tmp;
}
int pop()
{
node *tmp;
int n;
tmp = top;
n = tmp->data;
top = top->next;
free(tmp);
return n;
}
struct node
{
int data;
struct node
*next;
};
node *top;
top = NULL;

11. Applications of Stack
11
Expression Evaluation
Expression
Conversion
Syntax Parsing
Backtracking
Parenthesis
Check
String
Reversal
Function Call-
Recursion
Parameter Space & Local
Variables Processing

12. 12
QUEUE
A FIRST IN-FIRST OUT ARRANGEMENT OF DATA ITEMS

13. 13
Queue Features
Homogeneous Data
Members
Variable Length
FIRST IN – FIRST OUT
Front is An access pointer
for deletions
Rear is an access pointer
for insertions
Queue Operations
Enqueue()- Insert Element
at rear
Dequeue()- Delete Element
at front
Peek()- get the element at
front without removing it
isEmpty()- Check if the
queue is empty
isFull()- Check if the queue
is Full

14. 14
Operations

15. Implementation as an Array
15
int enqueue(int data)
{
if(isfull())
return 0;
rear = rear + 1;
queue[rear] = data;
return 1;
}
bool isfull() {
if(rear == size - 1)
return true;
else
return false;
}
int dequeue() {
if(isempty())
return 0;
int data =
queue[front];
front = front + 1;
return data;
}
bool isempty() {
if(front < 0 || front >
rear)
return true;
else
return false;
}
int size=5;
int queue[size];
int front=0;
Int rear=-1;

16. Implementation as a Linked List
16
void enqueue(queue *q, int
value)
{
node *tmp;
tmp = malloc(sizeof(node));
tmp->data = value;
tmp->next = NULL;
if(!isempty(q))
{
q->rear->next = tmp;
q->rear = tmp;
}
else
{
q->front = q->rear = tmp;
}
q->count++;
}
int dequeue(queue *q)
{
node *tmp;
int n = q->front->data;
tmp = q->front;
q->front = q->front-
>next;
q->count--;
free(tmp);
return(n);
}
struct node
{
int data;
struct node *next; };
struct queue
{
int count;
node *front;
node *rear; };
Void Initialize (queue *q)
{
q->count = 0;
q->front= NULL;
q->rear = NULL; }

17. Applications of Queue
17
•Serving requests on a single shared resource, like a
printer, CPU task scheduling etc.
•In real life scenario, Call Center phone systems uses
Queues to hold people calling them in an order, until a
service representative is free.
•Handling of interrupts in real-time systems. The
interrupts are handled in the same order as they arrive
i.e First come first served.