introduction to problem solving and programming

Course Code
CSE1021
Introduction to Problem Solving
and Programming
Unit -1
(8-Hours)
Dr. Sandip Mal
VIT Bhopal
VIT Bhopal University
Bhopal-Indore Highway, Kothrikalan, Sehore,
Madhya Pradesh – 466114.
Credits 4
Lecture -1

01
Unit
Introduction to Computer Problem
Solving

Unit -1
Introduction to Computer Problem Solving:
●Introduction – Problem Solving Aspect
●Top-Down Design
●Implementation of Algorithms (flowcharts, pseudo
code, programming language)
●Program Verification
●Efficiency of Algorithms
●Analysis of Algorithms.

Introduction
• Number of problems in our daily life.
• Suppose we have to calculate Simple Interest.
• Suppose we have to prepare a mark sheet.
 A computer is a DUMB machine.
 A computer cannot do anything alone without software
i.e. Program

Types of
Computer
Software
Overview
Describe here the topic of
the section
System Software
Example:-Operating
system is the type of
system software
Application Software
Example is Microsoft Office
Topic Features
Programming
Languages
C, C++,java,
Python

Software
• A software is a set of programs written to
solve a particular problem
• Software is a set of instructions on the basis of
which computer gives output/result.
• If the instructions are not correct, the
computer gives wrong result.

Never Ever Forget
• Just writing code is not sufficient to solve a problem.
• Program must be planned before coding in any computer
language available.
• There are many activities to be done before and after writing
code.

Fig. Steps in problem solving
Algorithm Development
Flowcharting
Documentation
Debugging and Testing
Compilation and Execution
Program Coding
Problem Analysis

Problem Analysis
• Process of becoming familiar with the problem.
• We need to analyze and understand it well before
solving.
• The user’s requirements cannot be fulfilled without clear
understanding of his/her problem in depth.
• Inadequate identification of problem may cause
program less useful and insufficient.
• Example: Banking Solution, Hospital Medical Study

Banking Problem Solved by
Software
●Digital transformation( Cash Deposit and Withdraw)
●Core Banking
●ATM- Solution
●Point of sale(POS)
●Third party( VISA, MasterCard)
●Policies run by Governments and other

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Algorithm Development
● A procedure for solving a mathematical problem in a finite
number of steps that may frequently involves repetition of
an operation.
OR
● A step-by-step procedure for solving a problem or
accomplishing some end
OR
● Developing an algorithm is a step of program design.

Differences Between
Program And Algorithm
Criteria Algorithm Program
Use Design Time Implementation Time
Who Domain Knowledge Programmer
Write In Any Language Programming
Language
H/w &
Software
Independent Dependent
Performance Analyze Testing

Step 1: Start
Step 2: Assume two numbers x and y and a variable sum=0
Step 3: Add two numbers x and y; store the value in variable sum
Step 4: If you want to try again with different numbers
then goto step 2
else
goto step 5
●Step 5: END
An Example of algorithm to find sum of two numbers

An algorithm to find sum of two
numbers:
Step 1: Start
Step 2: Declare variables num1, num2 and sum.
Step 3: Read values num1 and num2.
Step 4: Add num1 and num2 and assign the result to sum.
sum←num1+num2
Step 5: Display sum Step 6: Stop

Flowcharting
• Graphical representation of an algorithm using standard symbols.
• Includes a set of various standard shaped boxes that are
interconnected by flow lines.
• Flow lines have arrows(direction of flow).
• Activities are written within boxes in English.
• Communicates between programmers and business persons.

STAR
T
END
Read two
Numbers, A and B
Display C as Sum of A and B
C = A + B
Input
Start
Output
End
Processing

Coding
• The process of transforming the program logic design into computer
language format.
• An act of transforming operations in each box of the flowchart in terms of
the statement of the program.
• The code written using programming language is also known
● as source code.
• Coding isn’t the only task to be done to solve a problem using computer.
• Anyone can code. TRUST ME!!

Compilation
• Process of changing high level language into machine level
language.
• It is done by special software, COMPILER
• The compilation process tests the program whether it
● contains syntax errors or not.
• If syntax errors are present, compiler can not compile the
code.

Execution
• Once the compilation is completed then the program is linked
with other object programs needed for execution, there by
resulting in a binary program and then the program is loaded
in the memory for the purpose of execution and finally it is
executed.
• The program may ask user for inputs and generates outputs
after processing the inputs.

Debugging and Testing
• Testing ensures that program performs correctly the required task.
• Verification ensures that program does what the programmer
intends to do.
• Validation ensures that the program produces the correct results
for a set of test data.
• Test data are supplied to the program and output is observed.
• Expected output = Error free

Program Documentation
• Helps to those who use, maintain and extend the program
in future.
• A program may be difficult to understand even to
programmer who wrote the code after some days.
• Properly documented program is necessary which will be
useful and efficient in debugging, testing, maintenance
and redesign process.

Two types of documentations
1. Programmer’s Documentation (Technical
Documentation)
• Maintain, redesign and upgrade
• Logic, DFD, E-R, algorithm and flowchart
2. User Documentation (User Manual)
• Support to the user of the program
• Instructions for installation of the program

Types or levels of
Programming Languages
• High Level
● Low-level
– Machine Level
– Assembly Level

Low Level Language
• Statement or instruction is directly
translated into a single machine code.
• It is machine dependent, i.e. A particular
low- level language works only for a certain
machine.

Machine-level Language
• Language that a computer actually understands.
• 1’s and 0’s.
• A sequence of instructions written in the form of
binary numbers consisting of 1’s and 0’s
• It executes fast as computer don’t need
any translation.

Problem Solving
● Solving problems is the core of computer science.
● Programmers must first understand how a human solves a
problem.
● Then understand how to translate this "algorithm" into
something a computer can do.
● finally how to "write" the specific syntax (required by a
computer) to get the job done.
● It is sometimes the case that a machine will solve a problem in a
completely different way than a human.

Machine Language
ADVANTAGE DISADVANTAGE
Computer directly understands
machine instructions
Difficult to use
Directly starts executing Machine dependent
Takes less execution time Difficult to Debug and modify
It is relatively easy for writing programs in assembly languages, but is
slow in execution as it has to be converted into machine language
before execution.

Some examples of instructions for
assembly languages are as
follows:
CODE Meaning
ADD Addition
SUB Subtraction
INR Increase
DCR Decrease
CMP Compare

High Level Language
• User friendly, Similar to natural languages
• Platform independent
• Easy to write or remember
• Easy to learn and work
• While execution: translated into assembly language then to
machine language.
• Slow in execution but is efficient for developing programs.
• Ex: C, C++, Python, Java etc.

High Level Language
Advantages Disadvantages
Easy to use More execution time
Portability Needs own translator
Easy Debugging
Easy and Fast Development of
software

Compiler
• A high level source program must be translated into a form machine can
understand. This done by software called the compiler.
• Source code => Machine language code(Object code)
• During the process of translation, the compiler reads the source
● programs statement-wise and checks for syntax errors.
• In case of any error, the computer generates message about the error.
• Ex: C, C++, Java, FORTRAN, pascal etc.

Interpreter
• Like compiler, it is also a translator which translates high level
to machine level language.
• Translates and executes the program line by line.
• Each line is checked for syntax error and then converted to
● the equivalent machine code.
• Ex. QBASIC, PERL, PHP, ASP, PYTHON, RUBY

Difference between compiler
and interpreter
Compiler Interpreter
Compiler scans the entire program before
translating it into machine code
Interpreter translates and executes the
program line by line
Syntax errors are found only after the
compilation of complete programs
Syntax errors can be trapped after
translations of every line
It takes large amount of time to analyze the
source code but the overall execution time is
comparatively faster.
It takes less amount of time to analyze the
source code but the overall execution time is
slower.
Generates intermediate object code
which further requires linking, hence
requires more memory.
No intermediate object code is generated,
hence are memory efficient.

Top-Down Design
●If you have a big problem to solve, then a very
effective method of working towards a solution is
to break it down into smaller, more manageable
problems.
●This is the idea behind 'top-down design'.
Another term used is 'Stepwise refinement'.

Example
A software program is
needed to handle the lights in
a concert stadium. There are
hundreds of lights, all
producing complicated
sequences and effects.
Approach
Before a single line of code is
written, a structure chart is
drawn. Something like this:

Conti….
• A 'module' is ideally a self-contained block
of code.
• The code within has a clearly defined set of
inputs and outputs, this is called an
'interface'.
• Each module has a specific function to
perform. Its actions are controlled by a
master program loop.
• This is like the conductor in an orchestra,
making the whole thing work in harmony.

Conti..
●The control module is concerned with
controlling the hardware. It does this by
communicating and controlling a number
of sub-modules.
●These sub-modules are responsible for
certain types of light.

Divide-and-conquer
algorithm
● A divide-and-conquer algorithm works by recursively
breaking down a problem into two or more sub-problems of
the same or related type, until these become simple enough to
be solved directly.
● Divide/Break: This involves dividing the problem into some
sub problems.
● Conquer/Solve: Sub problem by calling recursively until sub
problem solved.
● Combine/Merge: The sub problem solved so that we will get
find problem solution.

Thanks!
Do you have any
questions?
sandip.mal@vitbhopal.ac.in

introduction to problem solving and programming

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