Computer Science Department FTSM Algorithm Knowledge: Understand algorithm representation using...

Computer Science Department FTSMFTSM

AlgorithmAlgorithm

Knowledge:Understand algorithm representation using flowchart and pseudocode

Skill:Map problem to solution in flowchart and pseudocode forms

TK1913-C ProgrammingTK1913-C Programming 22

Consider the following ….Problem: Baking a CakeHow to solve:

1. Start2. Preheat the oven at 180oC3. Prepare a baking pan4. Beat butter with sugar5. Mix them with flour, eggs and essence vanilla6. Pour the dough into the baking pan7. Put the pan into the oven8. End

Algorithm in Real LifeAlgorithm in Real Life


‘‘Divide and Conquer’ Strategy Divide and Conquer’ Strategy in Algorithmin Algorithm

Problem: Prepare a Breakfast

1. Start

2. Prepare a Breakfast

3. End


1. Start2. Prepare a Breakfast 2.1 Prepare a tuna sandwich 2.2 Prepare some chips 2.3 Make a cup of coffee3. End



1. Start2. Prepare a Breakfast 2.1 Prepare a tuna sandwich 2.1.1 Take 2 slices of bread 2.1.2 Prepare tuna paste 2.2 Prepare some chips 2.3 Make a cup of coffee3. End



1. Start2. Prepare a Breakfast 2.1 Prepare a tuna sandwich 2.1.1 Take 2 slices of bread 2.1.2 Prepare tuna paste 2.2 Prepare some chips 2.2.1 Cut potatoes into slices 2.2.2 Fry the potatoes 2.3 Make a cup of coffee3. End



1. Start2. Prepare a Breakfast 2.1. Prepare a tuna sandwich 2.1.1 Take 2 slices of bread 2.1.2 Prepare tuna paste 2.2. Prepare some chips 2.2.1 Cut potatoes into slices 2.2.2 Fry the potatoes 2.3. Make a cup of coffee 2.3.1 Boil water 2.3.2 Add water with sugar and coffee3. End



What is the connection What is the connection between these real life between these real life processes and processes and algorithm?algorithm?

Something to ponder …Something to ponder …


A specific and step-by-step set of instructions for carrying out a procedure or solving a problem, usually with the requirement that the procedure terminate at some point

2 types of algorithm representation will be explained:

Flowchart Pseudocode

Structured Method (will be explained later) A method of designing problem solution

AlgorithmAlgorithm


Flowchart represents algorithm graphically. It is intended for communication and documentation

FlowchartFlowchart


Flowchart – Basic SyntaxFlowchart – Basic Syntax

Start/End

SymbolSymbol SemanticSemantic

Process

Input/Output

Test

Connector

Flow of activities


Flowchart – Other SyntaxFlowchart – Other Syntax

Function call

SymbolSymbol SemanticSemantic

Magnetic Disc

Stored Data

Document/File

Multiple Document/File


Are the steps in the Are the steps in the algorithm discussed algorithm discussed earlier specific earlier specific enough to be enough to be executed by executed by computer?computer?



Problem Solving ProcessProblem Solving Process

InputInput ProcessProcess OutputOutput


Example 1Example 1Calculate and display the price of a number of apples if the quantity in kg and price per kg are given.

• QuantityQuantity

• Price_per_kgPrice_per_kg

PricePricePrice = Quantity * Price_per_kgPrice = Quantity * Price_per_kg



Flowchart: Calculate Price of Flowchart: Calculate Price of ApplesApples

InputInputQuantityQuantity

StartStart

Price Price Quantity * Price_per_kg Quantity * Price_per_kg

InputInputPrice_per_kgPrice_per_kg

OutputOutputPricePrice

EndEnd


void main() {

scanf(“%d”,&quantity);

scanf(“%d”,&price_per_kg);

price = quantity*price_per_kg;

printf(“%d”, price);

}

InputInputQuantityQuantity

StartStart

Price Price Quantity * Price_per_kg Quantity * Price_per_kg

InputInputPrice_per_kgPrice_per_kg

OutputOutputPricePrice

EndEnd

C Program: Calculate Price of ApplesC Program: Calculate Price of Apples


void main() {





}


It’s not complete! It’s not complete! Declare the variables…Declare the variables…


void main() {

int quantity, price_per_kg, price;





}

Well done ! But…Well done ! But…what are they?what are they?



void main() {


scanf(“%d”,&quantity);scanf(“%d”,&price_per_kg);



}

StartStart DeclarationDeclaration

} InputInput

ProcessProcess

OutputOutputEndEnd



Chapter 4Chapter 4

} Chapter 5Chapter 5

Chapter 6Chapter 6

Chapter 5Chapter 5

C Program: Calculate Price of ApplesC Program: Calculate Price of Applesvoid main() {


scanf(“%d”,&quantity);scanf(“%d”,&price_per_kg);



}


Example 2Example 2A car park has the following charges:

The 1st hour costs RM2.00. The subsequent hours cost RM1.00 per hour. Write an algorithm based on a vehicle’s entry and exit time.

• Entry_timeEntry_time

• Exit_timeExit_timeChargeCharge????????



Flowchart: Calculate Car Park Flowchart: Calculate Car Park ChargeCharge

Input Entry_timeInput Entry_timeInput Exit_timeInput Exit_time

StartStart

OutputOutputChargeCharge

EndEnd

Period Period Exit_time – Entry_time Exit_time – Entry_time

Period > 1?Period > 1?YesYes

Charge Charge 2 + (Period * 1) 2 + (Period * 1)Charge Charge 22 NoNo


scanf(“%d%d”,&entry_time,&exit_time);

period = exit_time – entry_time;

Input Entry_timeInput Entry_timeInput Exit_timeInput Exit_time

StartStart

OutputOutputChargeCharge

EndEnd

Period Period Exit_time – Entry_time Exit_time – Entry_time

Period > 1?Period > 1?YesYes

Charge Charge 2 + (Period * 1) 2 + (Period * 1)Charge Charge 22 NoNo

if (period > 1)charge = 2 + ( period *1);

elsecharge = 2;

printf(“%d”,charge);

Flowchart: Calculate Car Park Flowchart: Calculate Car Park ChargeCharge


void main() {

int entry_time, exit_time, period, charge;

scanf(“%d%d”,&entry_time,&exit_time);

period = exit_time – entry_time;

if (period > 1)charge = 2 + (period * 1);

elsecharge = 2;

printf(“%d”,charge);

}

} Chapter 7

C Program: Calculate Car Park C Program: Calculate Car Park ChargeCharge


Write a program to calculate the average mark of three TK1913’s students.

Example 3Example 3

• Mark AMark A

• Mark BMark B

• Mark CMark C

Average_markAverage_mark????????


THINK!!THINK!!


Identify the input and output of the problem. If necessary, use ‘Divide & Conquer’ strategy

to decompose the problem into smaller and manageable sub problems. Decompose the problem until all the sub problems can be solved to get the required results

For each sub problem, identify and list out the steps involved in solving it

Algorithm Development Algorithm Development GuidelinesGuidelines


What might be the What might be the disadvantage of disadvantage of flowchart?flowchart?



An outline of a program, written in a form that can easily be converted into real programming statements. It resembles the actual program that will be implemented later. However, it cannot be compiled nor executed.

Pseudocode normally codes the following actions:

Initialisation of variables Assignment of values to the variables Arithmetic operations Relational operations

PseudocodePseudocode


1. Start

2. Read quantityquantity

3. Read price_per_kgprice_per_kg

4.4. priceprice quantityquantity * price_per_kgprice_per_kg

5. Print priceprice

6. End

Example of PseudocodeExample of Pseudocode


Guidelines on Writing Guidelines on Writing PseudocodePseudocode

Refer to the Refer to the handouts in your handouts in your manual …. OK??manual …. OK??


CFlow DemonstrationCFlow Demonstration


End of Lecture 2End of Lecture 2

Yes !! That’s all? Yes !! That’s all? What’s next???What’s next???

INTRODUCTION TO CINTRODUCTION TO C on the way … on the way …

Computer Science Department FTSM Algorithm Knowledge: Understand algorithm representation using...

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