PROBLEM SOLVING. Instructor: Leo Lewis Course: Information Technology

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1 PROBLEM SOLVING Instructor: Leo Lewis Course: Information Technology

2 What you will learn What is problem solving The steps involved in problem solving Decomposing problems Algorithms and their representations To test an algorithm for correctness Top down design approach Book(s) Information Technology for CXC by Oxford Programming in Pascal by Kallicharan

3 What is Problem Solving A series of defined activities/steps that should lead to solving a problem, these activities include: A problem Definition a statement (a paragraph or series of paragraphs) outlining the nature of the problem Proposition and evaluation of solution the creation of one or more algorithms (pseudocode or flowcharts); truth tables Determination of most efficient solution comparison of algorithms to test for numbers of steps, no of variables dry, runs, etc Develop and represent algorithm using a programming language ( PASCAL ) Test and validate solution debugging

4 Problem Definition a statement (a paragraph or series of paragraphs) outlining the nature of the problem E.g. of some problem definitions: 1. Write an algorithm to find the average of three numbers 2. Find the aggregate of the marks earned by a student in his Easter Terminal Examination 3. To enter a them park children under 12 pay $300.00, children over 12 and adults pay $ and babies 2 years and under pay nothing. Input the number of persons entering the park. Read whether a person entering the park is an adult, child or baby and calculate the total revenue earned by the park for that day.

5 Proposition and evaluation of the solution the creation of one or more algorithms (pseudocode or flowcharts); truth tables E.g. of simple narrative 1. Get students mark for the following subjects Math, English, IT 2. Add the marks of each subject and divide the sum by three (3) 3. State the result

6 Now you try! Try to write the steps involved in solving the following problems: 1. Find the aggregate of the marks earned by a student in his Easter Terminal Examination 2. To enter a them park children under 12 pay $300.00, children over 12 and adults pay $ and babies 2 years and under pay nothing. Input the number of persons entering the park. Read whether a person entering the park is an adult, child or baby and calculate the total revenue earned by the park for that day. 3. VAT of 15% is added to the prices of an item. Input the name of an item and the price. Print the name of the item, the amount of VAT and the new price after VAT is added. 4. Input the name of a horse, the position it came in a race and the prize money received. The trainer is paid 5% of the prize money. Print the name of the horse, the position it came, the prize money and the amount paid to the trainer.

7 IPOS chart Every problem can be divided into four distinct components: Input the data to be received and is necessary to arrive at the correct output. Output the information or data to be produced Processing steps that change input into output or some intermediary value Storage variables and constants

8 So how do we break down a problem? Here is one problem: Write an algorithm to calculate the average of three numbers. So: What is/are the input(s)? What is/are the output(s)? What are the processing steps (how do we make output from input)? How do we store the values?

9 So how do we break down a problem? DID YOU SELL. SORRY. I MEAN DID YOU GET IT? INPUTS the three numbers OUTPUT the average PROCESSING add all three numbers together and divide the sum by three STORAGE VARIABLES (names given to each number) Three numbers number1, number2, number3 The Sum of the three numbers SUM The average - AVERAGE

Now you try! DIVIDE THE FOLLOWING PROBLEMS INTO INPUT, OUTPUT PROCESSING 1. Find the aggregate of the marks earned by a student in his Easter Terminal Examination 2.

Read whether a person entering the park is an adult, child or baby and calculate the total revenue earned by the park for that day. 3. VAT of 15% is added to the prices of an item.

10 Now you try! DIVIDE THE FOLLOWING PROBLEMS INTO INPUT, OUTPUT PROCESSING 1. Find the aggregate of the marks earned by a student in his Easter Terminal Examination 2. To enter a them park children under 12 pay $300.00, children over 12 and adults pay $ and babies 2 years and under pay nothing. Input the number of persons entering the park. Read whether a person entering the park is an adult, child or baby and calculate the total revenue earned by the park for that day. 3. VAT of 15% is added to the prices of an item. Input the name of an item and the price. Print the name of the item, the amount of VAT and the new price after VAT is added. 4. Input the name of a horse, the position it came in a race and the prize money received. The trainer is paid 5% of the prize money. Print the name of the horse, the position it came, the prize money and the amount paid to the trainer.

11 What are VARIABLES A variable is a symbolic name ( consisting of a list of characters, starting a letter) associated with a value and whose associated value may be changed. For example: the name sum can be used to store the sum of three numbers the name num1 can be used to store a number entered by a user; num1= 100 The name firstname can be used to store the name of persoon; firstname = Sugar The variable average can be used to store the average based on a calculation; average = ( )/3 The variable fullname can store the name of a person; fullname = Andre + Mullings

12 What are CONSTANTS A name for a value that, unlike a variable, cannot be re-associated with a different value For example: const float pi2 = ;

13 Advantages of variables and constants Remembering names might be easier than remembering actual values (Variables) you might need to change the values of variables at different points (Constant) keeping a value constant, nothing will change it.

14 Constants and Variables can: Store any value Be accessed and manipulated differently based on the value that is stored So what are the data types of values that can be stored in a variable or value: Integers what are integers? Floating point / Real numbers - Huh? Characters letters, punctuation marks, special characters, etc Literals / Strings list of characters whether letters, number or special characters stored as one name

15 Arrays another data type. sorta An array is a data type in which any kind of data type and any number of these data types can be stored as one name OR is a systematic arrangement of objects, usually in rows and columns (wikipedia)

Variable A variable is a value that can change during the execution of a program.

Declare and use variables and constants Variable A variable is a value that can change during the execution of a program. Constant A constant is a value that is set when the program initializes and does