The document discusses problem solving using computers. It explains that programming languages allow problems to be solved repeatedly by telling the computer the logic or algorithm to follow. An algorithm is a series of steps, like pseudocode or a flowchart, that represent the procedure for solving a problem. It then provides examples of algorithms for calculating the factorial of a number in different formats, including English steps, flowcharts, and pseudocode. Programming implements the algorithm by translating it line-by-line into source code.

1. Problem solving usingProblem solving using
ComputersComputers
By :
David Livingston J
Sudesh Kantila

2. Need for Programming LanguageNeed for Programming Language
1. We have some problem.
2. We have to solve the problem.
3. We can solve the problem, but we don’t
want to repeatedly solve the similar
problems.
4. We want to use the computer to do this
task for us whenever required.
5. We have to tell the computer, “How to
solve the problem.”

3. What is Problem?What is Problem?
 A problem is an obstacle which makes it
difficult to achieve a desired goal, objective
or purpose.
 It refers to a situation, condition, or issue
that is yet unresolved.
 In a broad sense, a problem exists when
an individual becomes aware of a
significant difference between what
actually is and what is desired.

4. What is Problem Solving?What is Problem Solving?
Every problem in the real world needs to
be identified and solved. Trying to find a
solution to a problem is known as
problem solving.
Problem solving becomes a part of our
day to day activity. Especially, when we
use computers for performing our day to
day activity.

5. How to solve a problem?How to solve a problem?
1. If you have a problem, either you can solve it
manually or using computer.
2. If the problem is easy enough, solve it
manually or else use computers.
3. Bigger problems can be sub-divided into
smaller problems (sub-problems) and start
solving them one by one.
4. After completing solving sub-problems, the
entire big problem has been solved easily.

6. Algorithm – Logic to solveAlgorithm – Logic to solve
If you have solved any problem already,
you would have definitely used some
procedure (logic) to do so.
There may be many different logic that can
solve a single problem.
You may write this logic into small steps
(easy enough) in english (or whatever
language you understand).
This block of steps to solve the problem is
called an “Algorithm”.

7. A simple problem - FactorialA simple problem - Factorial
We have to calculate the factorial of a
number ‘N’.
We know how to calculate the factorial.
Logic 1:
N! = N * N-1 * N-2 * …* N-(N-1) {N-(N-1)=1}
Logic 2:
N! = 1 * 2 * 3 * … * N
Logic 3:
N! = N * (N-1)! (Recursion)

8. Logic 1: (Algorithm)Logic 1: (Algorithm)
1. START
2. INPUT AN INTEGER – N
3. LET F=1
4. IF N > 1 GOTO STEP 5 ELSE STEP 8
5. F = F * N
6. N = N – 1
7. GOTO STEP 4
8. OUTPUT F
9. STOP

9. Logic 2: (Algorithm)Logic 2: (Algorithm)
1. START
2. INPUT AN INTEGER – N
3. LET F=1, X=1
4. IF X < N GOTO STEP 5 ELSE STEP 8
5. X = X + 1
6. F = F * X
7. GOTO STEP 4
8. OUTPUT F
9. STOP

10. Flow Chart – Graphical AlgorithmFlow Chart – Graphical Algorithm
Algorithms are written in some natural
language, e.g. – English, िहिन्दी, Chinease etc.
There may be some problem to understand
the algorithm if a person from different
region speaking a different language needs to
know the logic.
To overcome this problem, logic may be
represented in a graphical way.
This graphical representation of algorithm is
called ‘Flow Chart’

11. Flow Chart – Logic 1Flow Chart – Logic 1
LET F=1
IF
N > 1
INPUT N
START
OUTPUT F
START
F = F * N
N = N - 1
Yes
No

12. Flow Chart – Logic 2Flow Chart – Logic 2
LET F=1
X = 1
IF
X < N
INPUT N
START
OUTPUT F
START
X = X + 1
F = F * X
No
Yes

13. Common Flow Chart ShapesCommon Flow Chart Shapes
Flow Lines
Terminator
Input / Output Box
Process
Decision Box
(On Page and Off Page) Connectors
Predefined Process

14. PseudocodePseudocode
Pseudocode is a kind of structured english for
describing algorithms.
It allows the designer to focus on the logic of the
algorithm without being distracted by details of
language syntax.
At the same time, the pseudocode needs to be
complete. It describe the entire logic of the
algorithm so that implementation becomes a rote
mechanical task of translating line by line into
source code (coding).
Pseudocode cannot be compiled nor executed, and
there are no real formatting or syntax rules.

15. Pseudocode – Logic 1Pseudocode – Logic 1
GET value of N
SET initial value of F to 1
WHILE N > 1
F = F * N
N = N – 1
ENDWHILE
DISPLAY value of F

16. Programming (Coding) in CProgramming (Coding) in C
main()
{
int n;
long f=1;
printf(“Input n to get factorial: ”);
scanf(“%i”,&n);
while (n > 1)
{
f = f * n;
n = n – 1;
}
printf(“Factorial of %i is %li”,n,f);
retrun 0;
}