Introduction to data structures (ss)

Topics
Definitions
Introduction to Data structures
Classification of Data structures

Data:
• Collection of raw facts.
• Data are simply a value are set of values of different type which is called data types like
string, integer, char etc.
Structure: Way of organizing information, so that it is easier to use.
Data structure is
• representation of the logical relationship existing between individual elements of data.
• a specialized format for organizing and storing data in memory that considers not only
the elements stored but also their relationship to each other.
• about structuring or arranging and storing of data in such a way so that it can be accessed
and used efficiently.
Definition

 Data structure affects the design of both structural & functional aspects o
f a program.
Program = algorithm + Data Structure
 We know that a algorithm is a step by step procedure to solve a particula
r function.
 That means, algorithm is a set of instruction written to carry out certain
tasks & the data structure is the way of organizing the data with their
logical relationship retained.
 To develop a program of an algorithm, we should select an appropriate
data structure for that algorithm.
Therefore algorithm and its associated data structures form a program.
INTRODUCTION

Why Data Structure
 Human requirement with computer are going to
complex day by day.
 To solve the complex requirements in efficient way we n
eed this
 Provide fastest solution of human requirements.
 Provide efficient solution of complex problem.
– Space
– Time
 Data structures are the ways of organizing and storing d
ata in a computer so that we can perform several o
perations efficiently on it.
 It is widely used in every aspect of computer science.

The main idea behind Data structure is to
 reduces the memory usage of a Data Structure operation i.e., space complexity
 reduces the execution time of operations on Data Structure i.e., the time
complexity
Data Structures Study Covers:
 Amount of memory require to store
 Amount of time require to process
 Representation of data in memory
 Operatins performed on that data

As applications are getting complexed and amount of data is increasing day by day,
there may arrise the following problems:
Processor speed: To handle very large amout of data, high speed processing is
required, but as the data is growing day by day to the billions of files per entity,
processor may fail to deal with that much amount of data.
Data Search: Consider an inventory size of 120 items in a store, If our application
needs to search for a particular item, it needs to traverse 120 items every time,
results in slowing down the search process.
Multiple requests: If thousands of users are searching the data simultaneously on a
web server, then there are the chances that a very large server can be failed
during that process
In order to solve the above problems, data structures are used.
Need of Data Structures

Efficiency: Efficiency of a program depends upon the choice of data st
ructures.
For example: suppose, we have some data and we need to
perform the search for a perticular record. In that case, if we organize our
data in an array, we will have to search sequentially element by element.
hence, using array may not be very efficient here. There are better data
structures which can make the search process efficient like ordered array,
binary search tree or hash tables.
Reusability: Data structures are reusable, i.e. once we have implemented a p
articular data structure, we can use it at any other place.
Abstraction: Data structure is specified by the ADT which provides a level of
abstraction. The client program uses the data structure through interface on
ly, without getting into the implementation details.
Advantages of Data Structures

Primitive Data Structure
 These are basic structures and directly operated upon
by the machine instructions.
 Data structures that are directly operated upon the
machine-level instructions are known as primitive
data structures.
 Primitive data structures have different representation
s on different computers.
 Integer, Floating-point number, Character constants,
string constants, pointers etc, fall in this category.
 The most commonly used operation on data structure
are broadly categorized into :
◦ Create
◦ Selection
◦ Updating
◦ Destroy or Delete

 These are more sophisticated data structures.
 These are derived from primitive data structures.
 The non-primitive data structures emphasize on structuring of a group of
homogeneous (same type) or heterogeneous (different type) data items.
 Lists, Stack, Queue, Tree, Graph are example of non-primitive data structures.
 The most commonly used operation on data structure are broadly
categorized into following types:
• Create
• Selection
• Updating
• Searching
• Sorting
• Merging
• Destroy or Delete

Linear Data structures:
 Linear Data structures are kind of data structure that has homogeneous
elements.
 A data structure is called linear if all of its elements are arranged in the linear o
rder.
 In linear data structures, the elements are stored in non-hierarchical way wher
e each element has the successors and predecessors except the first and last
element.
 The data structure in which elements are in a sequence and form a liner series.
 Linear data structures are very easy to implement, since the memory of the
computer is also organized in a linear fashion.
 Some commonly used linear data structures are Stack, Queue and Linked Lists
 There are two ways to represent a linear data structure in memory.
 Static memory allocation
 Dynamic memory allocation

Arrays: An array is a collection of similar type of data items and each data item is
called an element of the array.
• The data type of the element may be any valid data type like char, int, float or
double.
• The elements of array share the same variable name but each one carries a
different index number known as subscript.
• The array can be one dimensional, two dimensional or multidimensional.
• The individual elements of the array age are:
age[0], age[1], age[2], age[3],......... age[98], age[99].
Types of Linear Data Structures

Linked List: Linked list is a linear data structure which is used to maintain
a list in the memory.
• It can be seen as the collection of nodes stored at non-contiguous memory
locations.
• Each node of the list contains a pointer to its adjacent node.
• In simple words, a linked list consists of nodes where each node contains a
data field and a reference(link) to the next node in the list.

Stack: Stack is a linear list in which insertion and deletions are allowed only at one end, called
top.
• A stack is an abstract data type (ADT), can be implemented in most of the programming
languages.
• It is named as stack because it behaves like a real-world stack,
for example: - piles of plates or deck of cards etc.
• Stack is a linear data structure which follows a particular order in which the operations are
performed.
• The order may be LIFO(Last In First Out) or FILO(First In Last Out).

Queue: Queue is a linear list in which elements can be inserted only at one
end called rear and deleted only at the other end called front.
• It is an abstract data structure, similar to stack. Queue is opened at both end
therefore it follows First-In-First-Out (FIFO) methodology for storing the data it
ems.

◦ A Non-Linear Data structures is a data structure in w
hich data item is connected to several other data i
tems.
◦ Non-Linear data structure may exhibit either a hi
erarchical relationship or parent child re
lationship.
◦ The data elements are not arranged in a sequential st
ructure.
◦ The different non-linear data structures are trees a
nd graphs
Non-Linear Data structures:

Trees: Trees are multilevel data structures with a hierarchical relationship among its elements
known as nodes.
• The bottommost nodes in the herierchy are called leaf node
• while the topmost node is called root node.
• Each node contains pointers to point adjacent nodes.
• Tree data structure is based on the parent-child relationship among the nodes.
• Each node in the tree can have more than one children except the leaf nodes
• whereas each node can have atmost one parent except the root node.
• Trees can be classfied into many categories
Types of Non Linear Data Structures

Graphs: Graphs can be defined as the pictorial representation of the set of elements
(represented by vertices) connected by the links known as edges.
• A Graph is a non-linear data structure consisting of nodes and edges.
• The nodes are sometimes also referred to as vertices and the edges are lines or arcs
that connect any two nodes in the graph.
• More formally a Graph can be defined as,
A Graph consists of a finite set of vertices(or nodes) and set of Edges which c
onnect a pair of nodes.
• A graph is different from tree in the sense that a graph can have cycle while the
tree can not have the one.

 Introduction to Data structures
 Classification of Data structures
Summary

Introduction to data structures (ss)

Introduction to data structures (ss)

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Introduction to data structures (ss)