Prepared By Mr. Vishal Patil

1. COMPUTER
PROGRAMMING
Lecture 04
Prepared By Mr. V. S. Patil Dept (CSE)/AEC

2. Unit 1 Problem Solving
Syllabus
Prepared By Mr. V. S. Patil Dept (CSE)/AEC

3. 2
1
Understand the logic of algorithm and flow of
control.
Understand the basics symbols of
flowcharts
Objectives

4. Algorithm
•An algorithm is well defined, finite set of computational
instructions that accomplishes a particular task, which may or
may not take inputs and produces some value or a set of
values as output. In addition all algorithms must satisfy the
following criteria:
1.Zero or more quantities are externally supplied: input
2.At least one quantity is produced: output
3.Each instruction is clear and unambiguous: Definiteness
4.The algorithm terminates after a finite number of steps:
Finiteness
5.For every input instance, it halts with the correct output:

5. Conventions used in writing Algorithms
•Name of Algorithm
•Introductory Comments
•Steps
•Comments

6. 1
Step 1: [input the three integers]
read x, y, z
.
Step 2: [compute the largest of three numbers]
big = x;
If(y>big) big=y
If(z>big) big=z
Step 3: [Write the largest number]
Write (big)
Step 4: [Finished] exit
Algorithm Development
Ex- Find maximum of 3 numbers. The variables used are:x, y, z : type integer
big : Storing the value of the largest number, type integer
2
3
4

7. Flowchart
• Definition:- A flowchart is graphical or pictorial
representation of an algorithm.
• It shows the logic of algorithm and flow of control.
• Flowchart uses the symbol to represent the specific
action and arrow to indicate the flow of control.

8. Basic symbols of flowchart

9. • Notice there are three types of symbols in this flowchart:
–rounded rectangles
–parallelograms
–a rectangle
• Each symbol represents a different type of operation.
Basic Flowchart Symbols

10. •Sequence
•Decision
•Repetition
•Case
Four Flowchart Structures

11. A series of actions are performed in sequence
The pay-calculating example was a sequence flowchart.
Ex.- Write an Flowchart for finding the addition of two number.
Sequence Structure

12. Decision Structure
•One of two possible actions is taken, depending on a condition.
•A new symbol, the diamond, indicates a yes/no question. If the
answer to the question is yes, the flow follows one path. If the
answer is no, the flow follows another path.
•Ex-
if (x < y)
a = x * 2;
else
a = x + y;

13. A repetition structure represents part of the program that repeats.
This type of structure is commonly known as a loop.
A loop tests a condition, and if the condition exists, it performs an
action.
Then it tests the condition again. If the condition still exists,
the action is repeated. This continues until the condition no
longer exists.
•Ex- while (x < y)
x++;
Repetition Structure
x < y? Add 1 to
x
YES

14. Case Structure
One of several possible actions is taken, depending on the
contents of a variable.
Ex- Find maximum of 3 nos

15. Question Bank
1.What is algorithm?
2. Explain Steps involved in algorithm development with
suitable example.
3.What is flowchart?
4.Describe the symbol of flowcharts.
5.Draw flowchart for Fibonacci Series.