chapter 2-problem solving methods

8/11/2019 Chapter 2-Problem Solving Methods

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CHAPTER 2PROBLEM SOLVING METHODS

FP 101PROGRAMMING PRINCIPLES

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Specific outcome:2. 1 Understand problem solving concept.2.2 Demonstrate the understanding of

Programming Life Cycle.2.3 Apply the different types of algorithm to

solve problem.2.4 Use problem solving tools to solve

problem

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2.1 Understand ProblemSolving Concept

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Problem Solving Concept

Identifying the problem --Which problem should I address? Ifthere are several, how do I choose the most important one?Describing the problem --How do I accurately and completelydescribe the problem?

Analyzing the problem --What are the different causes of theproblem, and which causes are most important to solve rightaway?Planning the solutions --What are the different alternativesolutions for solving the problem?

Imp lement ing the so lu t ions --How do I make sure the solutionsare implemented correctly and effectively?Monitoring/evaluating the solutions --How did the solutionswork? What needs to be changed?

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Developing the Input Process Output(IPO) Chart

Extends and organizes the information in the Problem

Analysis Chart.It shows in more detail what data items are input, whatare the processing or modules on that data, and whatwill be the result or output .

Input Processing OutputAll input

data fromPAC

All processing stepsfrom IPO / IC

All outputrequirements

from PAC

Define Input, ProcessAnd Output


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Developing the Input Process Output(IPO) Chart

ProblemWrite a Input Process Output (IPO) to find an area of acircle where area = pi * radius * radius

Input Processing Output

- radius - Area = 3.14 x radius x radius-Display area

- Area of a circle

Identify Input, ProcessAnd Output


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A program is required to read three (3) numbers,add them and print their total. It is usually helpfulto write down the three (3) components in adefining diagram as shown below:

Example


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Steps Of Program ExecutionInput Refers to the process of entering data, program andinstructions into the computer system using input devices.Process Computer processes raw data into usable information tobe used by user. Data processing is done by the CPU (CentralProcessing Unit).Output Output is raw data that has been processed by thecomputer (result). Output will be converted to an understandableform before being displayed or printed.

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Example: Flow Of ATMProgram

Assume that our transaction is moneywithdrawal. The instructions are:a. Get the card number from the user

b. Get pin number from the userc. Process the input datad. Get the transaction chosen by the usere. Get the account type from the user

f. Process the transaction as wanted by the userg. Withdraw amount of money required by the userh. Print receipt for the user

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(Input)

(Input)

(Input)

(Input)

(Process)

(Process)(Output)

(Output)


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Input : Example: Card number, ATM pin number, type oftransaction, type of account, amount of money towithdraw.

Process: Example: Process to identify card number, valid pin

number, type of transaction, type of account and deductsthe withdrawal from the users account. Output: Example: Receipt will show balance in users account and

money withdrawn.

INPUT PROCESS OUTPUT

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Executing A ProgramTo execute a program, CPU will examine each programinstruction in memory and send out the required commandsignals to carry out the instruction.During execution, data can be entered into memory and

manipulated in some specific way (delete and modify) asrequired.Program instructions are used to copy a program's data(program input) into memory.

After the input data were processed, instructions fordisplaying or printing will be executed.Result displayed by a program is called program output. Example: Cash withdrawal from ATM machine.

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First step: Data entered by user are stored in memory (input).

Second step: CPU will instruct program to process the card number and ATM

pin number with the data in memory concurrently. Program willexecute the transaction chosen by the user and store the result inmemory.

Third step:

The outputs are money withdrawal and receipt (output).

Machine languageprogram for processingcard number and PIN

number.

Data entered duringexecution.

Computed results.

Central Processing Unit.

Output results:

Receipt and money

Input data:Card Number,PIN Number,transaction. Program Output

Step 1

Step 2

Step 3

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Discuss

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1. Show step of mailing a copy of your SPMtranscript using photocopy machine.

2. Show step of making call from yourtelephone.

3. Show step of saving your document in yourcomputer.

4. Show steps of buying a tin of soft drink for a

vending machine.5. Show steps of sending an email to your

friend.


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ACTIVITY 1: GRAFFITI

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1. Everyone get a piece of graphic paper

2. Recall what you have learn in chapter 1 and chapter2 (2.1)

3. Write down 4 things that you have learned in class(only 3 parts)- 4 minutes

4. Move to your friends in class and share the answer(1 friend=1 answer)

5. Move again to other friends and share the answeruntil you fullfill 4 PARTS of PAPER

6. I will call 4 people to share the answer


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2.2 Demonstrate theunderstanding ofProgramming Life Cycle

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Programming Life Cycle

Life Cycle : Refers to the changes made froman old to a new program (the cycle startsagain).Programming Life Cycle : A framework ordiscipline, which uses certain techniquesneeded in computer programming

development.

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Steps involved in ProgrammingLife Cycle:

1. Specify theproblem

2. Analyze theproblem

3. Programdesign(thealgorithm)

4. Programcoding(Implem

ent thealgorithm)

5. Test andverify

6. Maintain andupdate

7.Documentation

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Step 1: Specify The Problem Describe exactly what you are doing as clear as

possible the data to be used, and what can be assumed.

Also, the desired output and its layout. Specification of needs

what the problem is

what is needed to solve itwhat the solution should provideif there are constraint s and special conditions.

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Example

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Situation:Joe Jambul was borrowing a book form PBU library.He was late returning a book late. Calculate thetotal fine charged to Joe Jambul by library for late-return books. The charge is RM0.20 for 1 day.

Calculate the total fine charged to Joe Jambul bylibrary for late-return books.Data given (RM 0.20/day)

Specify the problem:


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Step 3: Program Design

Definition:It is a framework or flow that shows the steps in

problem solving.

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Methods to design a program:

1. Algorithm Algorithm is a sequence of instructions to solve aproblem , written in human language , and it can solve

any problems when it is used with the correctprocedure. ( Example )2. Flowchart

A graphical representation of data, information and

workflow using certain symbols that are connected toflow lines to describe the instructions done in problemsolving.It shows the flow of the process from the start to the

end of the problem solving. ( Example )

Step 3: Program Design cont.

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ACTIVITY 2:DISCUSSION(20 minutes)

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1. Create 8 group (7 people/group)-

2 minutes2. Get a topic, marker pen, paper3. Discuss in group4. Write the algorithm in paper given5. Choose BEST GROUP as

WINNER(faster, correct , creative and

tidiness)


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PROBLEM

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You want to calculate the totaland average of four number thatentered by yourself. Then,

display the total and average.


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Basic flowchart symbol


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S y m b o l Explanat ion

Indicate the direction of data flow.Used to connect a block to another

block.Indicates operations / processinvolved.

Receive / read valueDisplay value

Flow Lines

Process

Input / Output




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S y m b o l Explana t ion

Execute decision based oncondition.Test is performed and theprogram flow continues, based onthe result

Indicates the beginning and end ofa flowchart.

Show the continuing flowchart inthe same page.

Decision

Start / End FlowLines

On-page

connector FlowLines




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START

Input

Condition

False statement

Output

END

False

True Statement True


Flowchart symbol usage


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Flowchart to calculate the total of fine for late returning of library books.RM0.20 perday

START

Inputtotal_of_day

Fine = total_of_day * 0.20

Output Fine

END

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Example Flowchart



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ACTIVITY 2:DISCUSSION(20 minutes)

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1. Create 8 group (7 people/group)-

2 minutes2. Get a topic, marker pen, paper3. Discuss in group4. Draw the flowchart in paper given5. Choose BEST GROUP as

WINNER(faster, correct , creative and

tidiness)


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3. PseudocodeSteps in problem solving that is written half inprogramming code and half in human language .

Advantages:Easily understood.Easily maintained.The codes are changeable.

Disadvantages:Cannot be executed in the computer.


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Example of Pseudocode

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START Input quiz1, quiz2, quiz3 TotalMark= quiz1+quiz2+quiz3 Print TotalMark

END


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4. Structure Charts An additional method in preparing programs thathas many sub modules .

It consists rectangular boxes, which represents allthe sub modules in a program and is connectedby arrows .It illustrates the top-down design of a program

and is also known as hierarchical chart becauseits components are in hierarchical form.The advantage is that it is easy to be drawn andto be changed.


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Structure Chart:The problem is normally big and complex.Thus, requires big program.Thus, the processing can be divided intosubtasks called modules.Each module accomplishes one function .

These modules are connected to eachother to show the interaction of processingbetween the modules.




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Structure chart


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ProblemWrite a Structure Charts to find an area of a circlewhere area = pi * radius * radius

Area

radius area = 3.14 xradius x radius Display area

Example Structure ChartStep 3: Program Design


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Problem: To calculate the amount of water bill

Represent the modules in the program

Water bill

Get /read

data

Computethe

charge

Displayinstructions

for user

Determinethe late

charge

Displaythe bill

Printthe bill

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Example Structure ChartStep 3: Program Design


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Steps 4: Program CodingDefinition: Writing problem solving into certainprogramming language such as C, COBOL , C++and others.Problem solving : Instructions before it is codedinto programming language.Purpose : To produce a program to develop asystemThe process of implementing an algorithm by

writing a computer program using a programminglanguage (for example, using C or C++ language)The output of the program must be the solution of

the intended problem .

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Step 5: Testing And Verify

Testing :Using a set of data to discover errors and toensure accuracy of the program.

Process of testing: is the process of executing aprogram to demonstrate its correctness

Program verification is the process of ensuringthat a program meets user-requirement

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Two types of error:

1. Syntax Error (grammatical error)Occurs when the rules of programming language are not applied .Correction is done during the programcoding.The bug can be traced during thecompilation .

Also known as compile-time errorMust be corrected before executing andtesting the program.

Step 5: Testing AndDebugging

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2. Logic errorCannot be traced by compiler.

Corrected during the problem solvingprocess.

Also known as run time error.Example : output for average is 4, but whenit runs, the output is 2.

Two types of error:

Step 5: Testing AndDebugging

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S 6 M i i A d


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Step 6: Maintain AndUpdateDefinition:

Activity that verifies whether the operational system isperforming as planned or an activity to modify thesystem to meet the current requirement .The process of changing a system after it has been

applied to maintain its ability. The changes mayinvolve simple changes such as error correcting.Process of changing a system after it has been

delivered and is in use. Adaptive Maintenance - modifications to properly

interface with changing environments -> newhardware, OS, devicesPerfective Maintenance - implementing new system

requirements after system is successful

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How to do maintenance?Testing Test the ability of the system.Measurement Access data time. Example, time tosave, print and others.Replacement Replace the old system to newsystem.

Adjustment Adding needs to new system.Repair For example: An old system cannot updatethe new dataUpdating Update the database.

Step 6: Maintenance

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Content of Documentation:

Description of the program.Specification of program requirementProgram design such as pseudocode and flowchartList of program and comments (to explain about the

program).Test results.Users manual book. Program capabilities and limitation.

Step 7: Documentation

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Two Pair Sharing

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In 5 minutes, write downanything that you have learned

in chapter 2.Choose your pair and share it.(5 minutes)

Pick 3 students from magic box


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Example 1

Write a program that will get 3 numbers asinput from the users. Find the average anddisplay the three numbers and its average.

Step 1: Define Problem

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Step 2: The Problem Analysis

Input:numbers1, number2 and number3.

Process:totalNumbers=number1+number2+number3average=totalNumbers/3

Output:The three numbers and its average

Example 1

INPUT PROCESS OUTPUT

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E l 1


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To calculate the average of three numbers.

1. Set Total=0, Average=0;2. Input 3 numbers3. Total up the 3 numbers

Total= total of 3 number

4. Calculate average Average=Total/3

5. Display 3 numbers and the average

Step 3: The Program Design

(using Algorithm)

Example 1

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E l 1


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Step 3: The Program Design

(using Pseudocode)

Example 1

E l 1


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Step 4: The Program CodingExample 1

#includevoid main(){float a,b,c,sum,av;couta>>b>>c;

sum=a+b+c;av=sum/3;cout


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2.3 Apply The DifferentTypes Of Algorithm To SolveProblem

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Concept Of Algorithm Algorithm:

Must may have input(s ) and must have output(s )Should not be ambiguous (there should not be differentinterpretations to it)Must be general (can be used for different inputs)Must be correct and it must solve the problem for whichit is designedMust execute and terminate in a finite amount of timeMust be efficient enough so that it can solve theintended problem using the resource currentlyavailable on the computer

Distinguish Between Flowchart


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Distinguish Between FlowchartAnd Pseudocode

TYPES FLOWCHART PSEUDOCODE

Layout Graphical structure Structure for thecode of the program

Benefits For smallerconcepts andproblems

More efficient forlarger programminglanguages

Structure Symbols andshapes

Linear text-basedstructure

Depth Detail can causeconfusion

More flexibility withdetail

Example 1


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Example 1

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A flowchart (and equivalent Pseudo code) tocompute the interest on a loan

Flowchart Pseudocode

Example 2


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Example 2

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A program that reads two numbers and displaysthe numbers read in decreasing order

Flowchart Pseudocode

Read A, BIf A is less than B

BIG = BSMALL = A

elseBIG = A

SMALL = BWrite (Display) BIG, SMALL

TIME FOR ACTIVITY!!


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TIME FOR ACTIVITY!!(30 minutes)

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Form a groupLeader in group find the question in class

Go to your groupDiscuss with your group memberWrite your answer in Majung Paper

(Algorithm, flowchart, pseudocode)Choose BEST GROUP as WINNER(faster, correct , creative and tidiness)


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EXERCISE

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1. Write IPO, pseudo code and flow chart forthe program which can calculate totalsale by multiply quantity and price.

2. Write an IPO, pseudo code and flow chartfor this program: any students whom gotCGPA more than 2.0 will pass their study,and less than 2.0 will fail.


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chapter 2-problem solving methods

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