Data Structures & Algorithms

Lecture 1: Foundational Data Structures

Ms. Joan Wakasa Murumba

Definitions A data type simply refers to a defined kind of

data, that is, a set of possible values & basic operations on those values.

When applied in programming languages, a data type defines a set of values & the allowable operations on those values.

Types of data in programming languages include integers, floating point numbers or characters, tuples, records, ADT, etc.

Definitions

Integers: Numbers that do not have decimal places

Floating point number: A real number (that is, a number that can contain a fractional part). The following are floating-point numbers:

3.0 , -111.5 , ½ , 3E-5 etc.

A Tuple A tuple is an ordered set of values. The separator for each value is often a comma

(depending on the rules of the particular language).

Common uses for the tuple as a data type are (1) for passing a string of parameters from one program to another, and (2) representing a set of value attributes in a relational database.

A Tuple An example of a tuple that emphasizes the

different data types that may exist within a tuple data type: 17,*,2.49,Seven

The above example is sometimes referred to as a 4-tuple, since it contains four values.

ADT

An Abstract Data type is defined as a mathematical model of the data objects that make up a data type as well as the functions that operate on these objects.

A set of data values and associated operations that are precisely specified independent of any particular implementation

A data type is abstract in the sense that it is independent of various concrete implementations

Examples of Abstract Data Type

Common abstract data types (ADT) typically implemented in programming languages include:

Arrays,Lists, Queues, Stacks and Trees.

Data Types

Data types are important in computer programmes because they classify data so that a translator can reserve appropriate memory storage to hold all possible values, e.g. integers, real numbers, characters, strings, and Boolean values

A Data Type Consists of:

A domain (a set of values) A set of operations that may be applied to

the values.

Data Type Classification Simple Data Type: This is where some data

items may be used singly The simple data types are classified as

follows: a. Characterb. Numeric integerc. Numeric reald. Boolean (logical).

Data Structures: May be combined together and arranged to form other data items

Data Structure

A data structure is the implementation of an abstract data type in a particular programming language.

Data structures can also be referred to as “data aggregate”.

A data structure is an organization of information, usually in memory, for better algorithm efficiency, such as queue, stack, list, and tree, or conceptual unity, such as the name and address of a person.

Data Structure

Data structures are collections of data values, the relationships among them and functions or operations that can be applied to that data.

Classification of Data StructuresData structures are broadly divided into two: Linear Data Structures Non-Linear Data Structures.

Linear Data Structures Linear data structures are data structures in

which individual data elements are stored and accessed linearly in the computer memory.

Examples include: lists, stacks, queues and arrays

Non-Linear Data Structures A non-linear data structure, as the name

implies, is a data structure in which the data items are not stored linearly in the computer memory, but data items can be processed using some techniques or rules.

Typical non-linear data structures are Trees.

Purposes of Data Structures For implementation of databases, e.g.,

trees Provide a means of handling large

amounts of data efficiently, e.g. Large database, indexing services, etc.

Efficient data structures are a key to designing efficient algorithms

A data structure example

Name Age Address Town position

Joshua 22 P. 0 BOX

2285

NYERI student

From the above data structure, data types can be

Data item Data type

Name Text, string

Age Integer, number,

Address Text, Alpha-numeric

Town Text

Position Text

Take Away Assignment

Q1. Computer Storage and management is key in programming and computing. Find out the relationship it has with data structures and

algorithms. Use suitable illustrations

Q2. Discuss in details A Stack data structure, giving its components, functions, operations, strengths and weaknesses and applications

Assignment Due on 13th July, 2014