Algorithms

USING ALGORITHMS TO SOLVE PROBLEMS:

What is an Algorithm?

An algorithm is a step-by-step procedure to solve a given problem.

Steps in algorithm writing:

Ø  Identify all the inputs and outputs required for solving a problem.

Ø  Identify additional data and constants needed.

Ø  Computation steps

Ø  Print / Display all the required results.

DIFFERENT PATTERNS IN ALGORITHMS:

There are mainly three different patterns of algorithms. They are as listed below-

1. Sequential – The steps represent sequence of occurrence of processing.
2. Conditional – Based on one or more conditions the instructions are divided
3. Iterational – Same set of instructions are repeated more than once until an end condition. These are also called Repetitive patterns.

EXAMPLES:

A. On Sequential Patterns

1.    Write an algorithm to find the sum of any two numbers.

Sol-                 Step 1: Start

                        Step 2: Read two numbers n1 and n2

                        Step 3: Sum = n1 + n2

                        Step 4: Print ‘Sum’

                        Step 5: Stop

2.    Write an algorithm to find the average of three numbers.

Sol-                 Step 1: Start

                        Step 2: Read three numbers n1, n2 and n3

                        Step 3: Avg = (n1 + n2 + n3) /3

                        Step 4: Print ‘Avg’

                        Step 5: Stop

3.    Write an algorithm to find the volume of a cylinder.

Sol-                 Step 1: Start

                        Step 2: Read radius (r) and height (h)

                        Step 3: Initialize constant,  P = 3.142

                        Step 4: Volume = Pr²h

                        Step 5: Print ‘Volume’

                        Step 6: Stop

4.    Write an algorithm to find the area and perimeter of a square.

Sol-                 Step 1: Start

                        Step 2: Read side of a square (a)

                        Step 3: Area = a²      and     Perimeter = 4a

                        Step 4: Print ‘Area’ and ‘Perimeter’

                        Step 5: Stop

5.    Write an algorithm to convert celcius into farenheit.

Sol-                 Step 1: Start

                        Step 2: Read temperature in celsius (c)

                        Step 3: f = 9c / 5 + 32

                        Step 4: Print temperature in farenheit (f)

                        Step 5: Stop

B. On Conditional Patterns

1.    Write an algorithm to find biggest of two numbers.

Sol-                 Step 1: Start

                        Step 2: Read two numbers (n1 and n2)

                        Step 3: if n1 > n2, go to Step 5

                        Step 4: Print “n2 is biggest” and go to Step 6

                        Step 5: Print “n1 is biggest”

                        Step 6: Stop

2.    Write an algorithm to check whether a given number is +ve, -ve or a zero.

Sol-                 Step 1: Start

                        Step 2: Read a number (n)

                        Step 3: if n > 0, go to Step 6

                        Step 4: if n < 0, go to Step 7

                        Step 5: Print “n is Zero” and go to Step 8

                        Step 6: Print “n is a +ve number” and go to Step 8

                        Step 7: Print “n is a –ve number”

                        Step 8: Stop

3.    Write an algorithm to check whether a given number is even or odd.

Sol-                 Step 1: Start

                        Step 2: Read a number (n)

                        Step 3: if remainder of n/2 is = 0, go to Step 5 

                                     or if n % 2 = 0, go to Step 5

                        Step 4: Print “n is odd” and go to Step 6

                        Step 5: Print “n is even”

                        Step 6: Stop

4.    Write an algorithm to find a person’s eligibility for voting, based on his/her age.

Sol-                 Step 1: Start

                        Step 2: Read the age of a person (age)

                        Step 3: if age > 18, go to Step 5

                        Step 4: Print “Person is not eligible for voting” and 

                                     go to Step 6

                        Step 5: Print “Person is eligible for voting”

                        Step 6: Stop

C. On Iterational Patterns

1.    Write an algorithm to print a number (5) 10 times.

Sol-                 Step 1: Start

                        Step 2: Initialize Counter to 1 (Count =1)

                        Step 3: Print ‘5’

                        Step 4: Count = Count + 1

                        Step 5: if Count < = 10 go to Step 3

                        Step 6: Stop

2.    Write an algorithm to print all the odd numbers between 1 and 10.

Sol-                 Step 1: Start

                        Step 2: Initialize Counter to 1 (Count =1)

                        Step 3: Print ‘Count’

                        Step 4: Count = Count + 2

                        Step 5: if Count < = 10 go to Step 3

                        Step 6: Stop

3.    Write an algorithm to print all the even numbers between 1 and 10.

Sol-                 Step 1: Start

                        Step 2: Initialize Counter to 2 (Count =2)

                        Step 3: Print ‘Count’

                        Step 4: Count = Count + 2

                        Step 5: if Count < = 10 go to Step 3

                        Step 6: Stop