Introduction to data structure

1. Introduction to Data
Structure
PROF. SUNIL D. CHUTE
DEPT. OF COMPUTER SCIENCE
M.G. ARTS SCIENCE AND LATE N.P. COMMERCE COLLEGE
ARMORI

2. A data structure is a way of storing data in a computer so that it
can be used efficiently and it will allow the most efficient algorithm to
be used. The choice of the data structure begins from the choice of
an abstract data type (ADT). A well-designed data structure allows a
variety of critical operations to be performed, using as few resources,
both execution time and memory space, as possible. Data structure
introduction refers to a scheme for organizing data, or in other words
it is an arrangement of data in computer's memory in such a way that
it could make the data quickly available to the processor for required
calculations.
A data structure should be seen as a logical concept that must address two
fundamental concerns.
1. First, how the data will be stored, and
2. Second, what operations will be performed on it

3. Fundamental of the Data Structure
A data structure is a specialized format of data for arranging and
storing data so that any user can easily access and worked within an
appropriate data to run a program efficiently. Computer memory
data can be organized logically or mathematically, and this process is
known as a data structure. In general, selecting a particular format of
data depends on two factors. The data must be rich enough to
satisfy the real relationships of the data in the real world. And on the
other hand, the data structure should be so simple that one can
easily process the data when it needs to be used.

4. Characteristics of data structures
 Following are the characteristics of the data structures as follows:
 Linear: A linear describes data characteristics whether the data items are
arranged in sequential form like an array.
 Non-Linear: A Non-Linear data structure describes the characteristics of data
items that are not in sequential form like a tree, graph.
 Static: It is a static data structure that describes the size and structures of a
collection of data items associated with a memory location at compile time
that are fixed. Example - Array.
 Homogenous: It is a characteristic of data structures representing whether the
data type of all elements is the same. Example- Array.
 Non-Homogenous: It is a characteristic of data structures representing
whether the data type elements may or may not be the same.

5. Characteristics of data structures
 Dynamic: It is a dynamic data structure that defines the shrinking and
expanding of data items at the run time or the program's execution. It is
also related to the utilization of memory location that can be changed at
the program's run time. Example: Linked list.
 It has some rules that define how the data items are related to each other.
 It defines some rules to display the relationship between data items and
how they interact with each other.
 It has some operations used to perform on data items like insertion,
searching, deletion, etc.
 It helps in reducing the usage of memory resources.
 Time Complexity: The execution time of a program in a data structure
should be minimum as possible.
 Space Complexity: The memory usage through all data items in a data
structure should be less possible.

6. Basic Operations of Data Structures
 Traversing: It is used to visit each variable once. It is also referred to as
visiting elements in the data structure.
 Searching: It is used to find the location of a given element in the whole
data structure. Example, an array.
 Insertion: It is used to insert an element at the specified position in data
elements.
 Deletion: A deletion operation is used to delete an element from the
specified location.
 Sorting: It is used to arrange or sort the data elements in ascending or
descending order. However, the data items are arranged in some logical
order, such as Name key, account number, etc.
 Merging: The Merge operation is used to join two or more sorted data
elements to a data structure.

7. SORTING METHODS
BUBBLE SORT
INSERTION SORT
SELECTION SORT
MERGE SORT

8. What is sorting?
 Sorting refers to the operation or technique of arranging and rearranging
sets of data in some specific order. A collection of records called a list where
every record has one or more fields. The fields which contain a unique value
for each record is termed as the key field. For example, a phone number
directory can be thought of as a list where each record has three fields -
'name' of the person, 'address' of that person, and their 'phone numbers'.
Being unique phone number can work as a key to locate any record in the
list.
 Sorting is the operation performed to arrange the records of a table or list in
some order according to some specific ordering criterion. Sorting is
performed according to some key value of each record.
 The records are either sorted either numerically or alphanumerically. The
records are then arranged in ascending or descending order depending on
the numerical value of the key. Here is an example, where the sorting of a
lists of marks obtained by a student in any particular subject of a class

9. Categories of Sorting
 The techniques of sorting can be divided into two
categories. These are:
• Internal Sorting
• External Sorting
 Internal Sorting: If all the data that is to be sorted
can be adjusted at a time in the main memory, the
internal sorting method is being performed.
 External Sorting: When the data that is to be sorted
cannot be accommodated in the memory at the same
time and some has to be kept in auxiliary memory
such as hard disk, floppy disk, magnetic tapes etc,
then external sorting methods are performed.

10. complexity of sorting algorithm
 The complexity of sorting algorithm calculates the running time
of a function in which 'n' number of items are to be sorted. The
choice for which sorting method is suitable for a problem
depends on several dependency configurations for different
problems. The most noteworthy of these considerations are:
• The length of time spent by the programmer in programming a
specific sorting program
• Amount of machine time necessary for running the program
• The amount of memory necessary for running the program

11. Efficiency of sorting Techniques
 To get the amount of time required to sort an array of 'n' elements by a
particular method, the normal approach is to analyze the method to find the
number of comparisons (or exchanges) required by it. Most of the sorting
techniques are data sensitive, and so the metrics for them depends on the
order in which they appear in an input array.
 Various sorting techniques are analyzed in various cases and named these
cases as follows:
• Best case
• Worst case
• Average case
 Hence, the result of these cases is often a formula giving the average time
required for a particular sort of size 'n.' Most of the sort methods have time
requirements that range from O(nlog n) to O(n2).