This document discusses data structures stacks and queues. It defines them as last-in first-out and first-in first-out data arrangements, respectively. It covers their structures, common operations like push, pop, enqueue and dequeue. Applications of stacks include expression evaluation, backtracking, and recursion. Applications of queues include task scheduling, print job handling, and call centers. The document provides examples of implementing stacks and queues using both arrays and linked lists.

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.