Lecture 2 Data Structure Introduction

Lecture 2
Advanced Data structures
&
Analysis of Algorithms
Abirami S
Asst.Prof. IT Dept.
Shah and Anchor Kutchhi Engineering
College, Mumbai

Data Structures
A data structure is a particular way of
organizing data in a computer so that it can be
used effectively.

Need of Data Structures
• Processor speed: To handle very large amount 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 106 items in
a store, If our application needs to search for a
particular item, it needs to traverse 106 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.

Advantages of Data Structures
• Efficiency: Efficiency of a program depends upon the choice of
data structures. For example: suppose, we have some data and
we need to perform the search for a particular 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 particular data structure, we can use it at any
other place. Implementation of data structures can be compiled
into libraries which can be used by different clients.
• Abstraction: Data structure is specified by the ADT which
provides a level of abstraction. The client program uses the data
structure through interface only, without getting into the
implementation details.

Classification of Data Structures

Linear Data Structures:
• A data structure is called linear if all of its
elements are arranged in the linear order.
• In linear data structures, the elements are
stored in non-hierarchical way where each
element has the successors and predecessors
except the first and last element.

• Static Data structure:
In Static data structure the size of the
structure is fixed.
• The content of the data structure can be
modified but without changing the memory
space allocated to it.

Dynamic Data Structure:
• In Dynamic data structure the size of the
structure in not fixed and can be modified
during the operations performed on it.
• Dynamic data structures are designed to
facilitate change of data structures in the run
time.

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.

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.

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.

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 items.

Non Linear Data Structures:
• This data structure does not form a sequence
i.e. each item or element is connected with
two or more other items in a non-linear
arrangement.
• The data elements are not arranged in
sequential structure.

Trees:
• Trees are multilevel data structures with a hierarchical
relationship among its elements known as nodes.
• The bottommost nodes in the hierarchy 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.

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 different from tree in the sense that
a graph can have cycle while the tree can not
have the one.

Lecture 2 Data Structure Introduction

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