DIVIDE AND CONQUER STRATEGY, DATA TYPE, ALGORITHM DESIGN AND PRACTICE.

Week 13

Mr.M

oh

am

me

d R

ah

ma

th

DIVIDE AND CONQUER STRATEGY

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. The solutions to the sub-problems are then combined to give a solution to the original problem.

Mr.M

oh

am

me

d R

ah

ma

th

Mr.M

oh

am

me

d R

ah

ma

th

ADVANTAGES OF DIVIDE AND CONQUER STRATEGY

Solving difficult problems Algorithm efficiency Parallelism Memory access Roundoff control

Mr.M

oh

am

me

d R

ah

ma

th

DATA TYPE

Data type is define as the type of data. Example: integers, Boolean, characters, floating-

point numbers, alphanumeric strings…

Mr.M

oh

am

me

d R

ah

ma

th

ALGORITHM

Definition : an algorithm is a step-by-step procedure for calculations. Algorithms are used for calculation, data processing, and automated reasoning.

Mr.M

oh

am

me

d R

ah

ma

th

STEPS IN DEVELOPMENT OF ALGORITHMS

1. Problem definition2. Development of a modal3. Specification of Algorithm4. Designing an Algorithm5. Checking the correctness of Algorithm6. Analysis of Algorithm7. Implementation of Algorithm8. Program testing9. Documentation Preparation

Mr.M

oh

am

me

d R

ah

ma

th

EXAMPLEQ) Write a algorithm to find out number is odd or

even?• step 1 : start• step 2 : input number• step 3 : rem=number mod 2• step 4 : if rem=0 then•                print "number even"•            else•                print "number odd"•            endif• step 5 : stop

Mr.M

oh

am

me

d R

ah

ma

th

Q) Write an algorithm to add two numbers entered by user.

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

Mr.M

oh

am

me

d R

ah

ma

th

Q) Write an algorithm to check whether a number entered by user is prime or not.

• Step 1: Start • Step 2: Declare variables n,i,flag. • Step 3: Initialize variables flag←1 i←2 • Step 4: Read n from user. • Step 5: Repeat the steps until i<(n/2) 5.1 If remainder of

n÷i equals 0 flag←0 Go to step 6 5.2 i←i+1 • Step 6: If flag=0 Display n is not prime else Display n is

prime • Step 7: Stop

Mr.M

oh

am

me

d R

ah

ma

th

Q) Write an algorithm to find the largest among three different numbers entered by user.

Step 1: Start Step 2: Declare variables a,b and c. Step 3: Read variables a,b and c. Step 4: If a>b If a>c Display a is the largest

number. Else Display c is the largest number. Else If b>c Display b is the largest number. Else Display c is the greatest number.

Step 5: Stop

Mr.M

oh

am

me

d R

ah

ma

th

SESSION 13END

Mr.M

oh

am

me

d R

ah

ma

th