c_programming, Introduction to C,computer, algorithm

1. Idea of Algorithm

4. Features of an Algorithm
• Must be Precise.
• Must be Unambiguous.
• Should be completed in finite number of
steps.
• No instruction must be repeated infinitely.
• Each step must follow a specified order.
• After termination, desired result must be
obtained.

6. Example
• Test the equality of two numbers.
o Step 1: Start
o Step 2: Input first number as A
o Step 3: Input second number as B
o Step 4: if A=B
then print “Equal”
else
Print “Not Equal”
o Step 5: Stop

7. Example
• To print the first 10 natural numbers.
oStep 1: Start
oStep 2: [initialization] set i=1, n=10
oStep 3: Repeat step while i<=n
oStep 4: print i
oStep 5: Stop

8. Example
• To find sum of N natural numbers.
oStep 1: Start
oStep 2: Input N
oStep 3: [initialization] set i=1, sum=0
oStep 4: Repeat step while i<=N
oStep 5: set sum= sum+ i
Set i=i+1
oStep 4: print sum
oStep 5: Stop

9. Other Examples
1. Algorithm to find largest of three numbers.
2. To find whether a number is even or odd.
3. To find average of first N natural numbers.
4. To interchange / swapping of two variables.
Using/without using third variable.
5. To find area of a circle of radius r.
6. To find simple interest and compound interest for
principal p, rate r and time t.
7. To find roots of a quadratic equation.

11. Flow Chart
• Graphical representation of steps followed to
solve a given problem.
• Flow chart helps the viewers to visualize the
logic of the solution of a problem.
• In flow chart, each step is depicted by a
symbol and is associated with a short
description.

13. • Calculate the sum of first 10 natural numbers.
start
Set i=1 and Sum=0
Set sum=sum+i and i=i+1
Is i>10?
Display Sum
End
No
Yes

14. Pseudo Code
• It is a compact informal high-level description
of an algorithm that uses the structural
conventions of programming language.
• Pseudo codes are an outline of a program that
can easily be converted into programming
statements.

15. Keywords used while writing pseudo
codes:
1. IF (age>=18) then
display eligible to vote
ELSE
display not eligible
END IF

16. 2. WHILE (i<10)
print i
increment i by 1
END WHILE
3. FOR each student in the class
add 10 as bonus marks
END FOR