Problem solving methodology

PROBLEM SOLVING
METHODOLOGY
Prof. K ADISESHA (Ph. D)

Contents-
Introduction
Programming Error
Programming Constructs
Programming Approaches
2
Prof. K. Adisesha (Ph. D)
Problem-solving process
Programming techniques

INTRODUCTION
3
Definition:
“Computer is an electronic machine that can store, recall and process
data. It can perform tasks or complex calculation according to a set of
instructions or programs.”
 The term problem solving is used in many disciplines, sometimes with
different perspectives and often with different terminologies.
 The problem-solving process starts with the problem specification and
end with a correct program.

PROBLEM SOLVING
Problem-solving process:
The steps to follow in the problem-solving process are:
 Problem definition
 Problem Analysis
 Problem Designing
o Algorithm, Flow Chart and Pseudo-code development
 Coding
 Testing & Debugging
 Documentation & Maintenance
4

PROBLEM SOLVING
Problem definition:
The problem solver must understand problem very well to solve problem
efficiently:
 This step defines the problem thoroughly.
 Here requirements are specified.
 This step includes understanding the problem very well.
5

PROBLEM SOLVING
Problem Analysis:
Analyzing the problem or analysis involves identifying the following:
 Inputs, i.e. the data you have to work with.
 Outputs i.e. the desired results.
 Any additional requirements on the solutions.
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PROBLEM SOLVING
ALGORITHM:
An Algorithm is a step-by-step procedure to solve a given problem:
 The word algorithm originates from the word ‘algorism’ which
means process of doing arithmetic with Arabic numerals.
 In 9th-century Arab Mathematician, Mohammed Al-Khowarizmi,
who developed methods for solving problems which is, used specific
step-by-step instructions
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ALGORITHM
Characteristics of algorithm:
A well defined algorithm has the five basic characteristics as follows:
1. Input: Algorithm starts with procedural steps to accept input data. The algorithm
must accept one or more data to be processed.
2. Definite: Each operational step or operation must be definite i.e. each and every
instruction must clearly specify that what should be done.
3. Effective: Each operational step can at least in principle is carried out by a person
using a paper and pencil in a minimum number of times.
4. Terminate: After some minimum number operation algorithm must come to an end.
5. Output: An algorithm is written to solve the problem, therefore it must produce one
or more computed result or answer called output.
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ALGORITHM
Example of algorithm:
Design an algorithm to find the area of a rectangle:
Given the length l and the breadth b, this algorithm finds the area of rectangle rec.
 Step 1: START
 Step 2: [Read the vales of l, b]
INPUT l, b
 Step 3: [Calculate are of rectangle]
rec = l * b
 Step 4: [Print the area of rectangle]
OUTPUT rec
 Step 5: [End of Algorithm]
STOPProf. K. Adisesha (Ph. D)
9

ALGORITHM
Example of algorithm:
Design an algorithm to find the average of four numbers:
 Step 1: START
 Step 2: INPUT A, B, C, D
 Step 3: [Calculate] AVG = (A+B+C+D)/4
 Step 4: OUTPUT AVG
 Step 5: STOP
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ALGORITHM
Advantage of Algorithm:
 It is a step-by-step representation of a solution to a given problem, which is very
easy to understand.
 It has got a definite procedure, which can be executed within a set period of time.
 It is independent of programming language.
 It is easy to debug as every step has got its own logical sequence
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ALGORITHM
Disadvantage of Algorithm:
 It is time-consuming
 An algorithm is developed first which is converted into a flowchart and then into a
computer program.
12

ALGORITHM
Analysis of Algorithm:
There may be more than one approach to solve a problem.
 The choice of a particular algorithm depends on the following performance analysis
and measurements.
 Space complexity: The amount of memory needed by the algorithm to complete
its run.
 Time Complexity: The amount of time, the algorithm needed to complete its
run.
13

ALGORITHM
Analysis of Algorithm:
When we analyze an algorithm depends on input data, there are three
cases.
 Best Case
 Average Case
 Worst Case
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FLOWCHART
Definition:
A Flowchart is a pictorial or graphical representation of an algorithm.
 Flowchart plays an important role in the programming of a problem and helpful in
understanding the logic of program.
 Once the flow chart is drawn, it becomes easy to write program in any high level
language.
 Flowcharts are classified into two categories:
 Program Flowcharts
 System Flowcharts
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FLOWCHART
Definition:
A Flowchart is a pictorial or graphical representation of an algorithm.
 Program Flowcharts:
 Program flowcharts present a diagrammatic representation of a sequence of
instructions for solving a program.
 System flowcharts:
 System flowcharts indicate the flow of data throughout a data processing
system, as well as the flow into and out of the system.
 Such flowcharts are widely used by designers, to explain a data processing
system.
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FLOWCHART
Importance of Flowchart:
 Communication: Flowcharts are better way of communication of the logic of a
program.
 Effective Analysis: With the help of flowchart, problem can be analyzed in more
effective way.
 Proper documentation: Program flowcharts serve as a good program documentation,
which is needed for various programs.
 Efficient coding: The flowchart acts as guide or blueprint during the system analysis
and program development phase.
 Proper Debugging: The flow chart helps in debugging process.
 Efficient program maintenance: The maintenance of a program become easy with
the help of flowcharts.Prof. K. Adisesha (Ph. D)
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FLOWCHART
Symbols Used In Flowcharts:
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FLOWCHART
Symbols Used In Flowcharts:
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FLOWCHART
Example of Flowcharts:
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FLOWCHART
Example of Flowcharts:
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FLOWCHART
Advantage of Flowcharts:
 Flowcharts provide an excellent means of communication, which is very easy
to understand.
 It has got a definite procedure, which shows all the major parts of a program,
It is easy to convert it into a program.
 It is independent of programming language.
 It is easy to debug as every step has got its own logical sequence.
22

FLOWCHART
Disadvantages of Flowcharts:
 It is time-consuming and it requires the uses of a number of symbols which
are to be properly represented.
 The represented of complex logic is difficult in a flowchart.
 Alterations and modifications can be only made by redrawing the flowcharts.
23

PSEUDO CODE:
Definition:
This is an abstract representation of program in English statement. .
 In Pseudo code English words & phrases are used to represent operations.
 Advantages:
 Easy to read, understand & modify.
 Disadvantages:
 It is only a partial code.
 It cannot be used to execute the and obtain the result.
24

PROBLEM SOLVING
Coding or Programming:
The process of writing program instructions for an analyzed problem in a
programming language.
 It is the process of translating the algorithm or flowchart into the syntax of
given purpose language.
 You must convert each step of the algorithm into one or more statements in a
programming language such as C, C++, and Java etc.
25

PROBLEM SOLVING
Testing and Debugging:
Testing:
 It is the process of checking whether the program works according to
the requirement of the user.
Debugging:
 It is the process of identifying and correcting or removing the Bugs
(errors).
26

PROBLEM SOLVING
Testing and Debugging:
 There are four types of errors.
 Syntax errors
 Run-time errors
 Semantic errors
 Logic errors (bugs)
27

ERRORS
Syntax Error:
 Syntax is the set of rules which should followed while creating the statements of
the program.
 The grammatical mistakes in the statements of the program are called syntax errors.
 Example: void main( )
{ int a, b;
cout << ‘Enter the numbers”
cin >> a >> b;
cout << a + b
}
 In the example program, the Second & fourth statement produces an syntax error as the
missing semicolon.Prof. K. Adisesha (Ph. D)
28

ERRORS
Semantic Error:
 An error, which occurs due to improper use of statements in programming language.
o Consider an expression C = A + B, indicating the values of the variable A and B are added
and assigned to variable C.
o If we written A + B = C, through the values of A and B are added, it cannot be assigned to
variable C written to the right of = Sign.
 This is semantic error
Run-time Error:
 During execution of the program, some errors may occur.
 Such errors are called run-time errors.
 Example: Divide by zero.
29

ERRORS
Logical Error:
Logical errors occur when there are mistakes in the logic of the program.
 Unlike other errors logical errors are not displayed while compiling because the
compiler does not understand the logic of the program.
 Example:
o To find the area of the circle, the formula to be used is area = 3.14 * r * r.
o But if we written area = 3.14 * 2 * r, then the required output is not obtained
even though the program is successfully executed.
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PROBLEM SOLVING
Documentation and Maintenance:
Documentation is a reference material which explains the use and maintenance
of the program application for which it has been written.
 There are two types of documentation.
o Internal Documentation
o External Documentation.
31

DOCUMENTATION
Internal Documentation:
This is also known as technical documentation.
 It is meant for the programmer who may update the program code at later
stages.
 It is done by:
o Defining meaningful variable names.
o Including comments in program code.
o Presenting the program code clearly.
32

DOCUMENTATION
External Documentation:
The program or application is supported with additional textual
information about the application.
 It is useful for the user, administrator or developer.
33

MAINTENANCE
Maintenance:
Program maintenance means periodic review of the programs and
modifications based on user’s requirements.
 Documentation plays an important role in program maintenance.
 It helps speedy and efficient maintenance.
 Maintenance is a continuous task
34

PROGRAMMING CONSTRUCTS
Programming Constructs:
A programming constructs is a statement in a program.
 There are 3 basic programming constructs.
 Sequential Constructs
 Selection Constructs
 Iteration Constructs
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Sequential Constructs:
The program statements are executed one after another, in a sequence.
 Sequential constructs are.
 Input Statement
 Assignment Statement
 Output Statement
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Sequential Constructs:
Input Statement:
 This statement is used to input values into the variables from the input device.
 Example: INPUT A, B, C
Assignment Statement:
 This statement is used to store a value in a variable.
 In many languages ‘=’ is used as the assignment operator.
 Example: A = 10;
B = 5;
C = A + B;
Output Statement:
 This statement is used to display the values of variables on the standard output device.
 Example: OUTPUT C;
37

Selection construct:
It is also known as conditional construct.
 This structure helps the programmer to take appropriate decision.
 There are five kinds of selection constructs, viz.
 Simple – if
 if – else
 if – else – if
 Nested – if
 Multiple Selection
38

Iterative Constructs or Looping:
The process of repeated execution of a sequence of statements until some
condition is satisfied is called as iteration or repetition or loop.
 Iterative statements are also called as repetitive statement or looping
statements.
 There are two iterative constructs, viz.
 Conditional Looping
 Unconditional Looping
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ITERATIVE CONSTRUCTS
Conditional Looping:
This statement executes a group of instructions repeatedly until some
logical condition is satisfied.
 The number of repetitions will not be known in advance.
 The two conditional looping constructs are:
 While loop:
 This is a pre-tested loop structure.
 This structure checks the condition at the beginning of the structure
 do-while loop:
 This is a post-tested loop structure.
 This structure checks the condition at the end of the structureProf. K. Adisesha (Ph. D)
40

ITERATIVE CONSTRUCTS
Unconditional Looping:
This statement executes a group of instructions is repeated for specified
number of times.
 The unconditional looping constructs is:
 for statement:
 This structure is the fixed execution structure.
 This structure is usually used when we know in advance exactly how many
times asset of statements is to be repeatedly executed again and again.
 The general form of for structure is as follows:
for ( Expression 1; Expression 2; Expression 3)
{ Statements; }
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Characteristics of a good program:
The best program to solve a given problem is one that requires less space in memory,
takes less execution time, easy to modify and portable:
 Modification: A good program is the one which allows any modifications easily
whenever needed.
 Portability: A good program is the one which can be run on different type of machine
with a minimum or no change.
42

PROGRAMMING APPROACHES
Approaches to problem solving:
The various approaches to solve a problems depends upon various problem designing
methods, in which system details are developed first, followed by major process.
 The various approaches are:
 Top-down design
 Stepwise refinement
 Bottom-up design
43

Approaches to problem solving:
Top-down design:
 Top-down design involves dividing a problem into sub-problems and further dividing the sub- problems
into smaller sub-problems until it leads to sub-problems that can be implemented as program statements.
Stepwise refinement:
 The process of breaking down the problem at each stage to obtain a computer solution is called stepwise
refinement
Bottom-up design:
 A design method, in which system details are developed first, followed by major process. This approach
is the reverse of top-down design.
 The process starts with identification of set of modules which are either available or to be constructed. An
attempt is made to combine the lower level modules to form modules of high level.
 Examples include object oriented programming using C++.
44

Programming techniques:
The various programming techniques are:
 Unstructured programming
 Procedural programming
 Structured programming
 Modular programming
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PROGRAMMING TECHNIQUES
Unstructured programming:
 During learning stage by writing small and simple programs
without planning leads to unstructured programming.
Procedural programming:
 This method allows us to combine the returning sequences of
statements into one single place.
 A procedure call is used to invoke the procedure. After the sequence is processed,
flow of control proceeds right after the position where the call was made.
 Procedures (sub procedures) programs can now be written as more structured and
error Free.
46

Structured programming:
 Structured programming is method of programming by using the following type of
code structures to write program:
 Sequence (input, output, assignment)
 Selection (if, if-else etc.)
 Iteration (while, do-while, for)
 Subroutines (functions)
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Modular programming:
The process of splitting the lengthier and complex programs into number of smaller units
(modules) is called modularization and programming with such an approach is called
modular programming.
 This technique provides grouping of procedures which are common functionality into
separate modules.
 Advantages of modular programming:
 Reusability
 Debugging is easier
 Building library
 Portability
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Discussion
49
Queries ?
Prof. K. Adisesha
9449081542

Problem solving methodology

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