slide 02 - algorithm

8/10/2019 Slide 02 - Algorithm

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Computer Science Department FTSM

Algorithm

Knowledge:

Understand algorithm representation using flowchart andpseudocode

Skill:

Map problem to solution in flowchart and pseudocode forms


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TK1913-C Programming 2

Consider the following .

Problem:Baking a Cake

How to solve:

1. Start

2. Preheat the oven at 180oC

3. Prepare a baking pan

4. Beat butter with sugar

5. Mix them with flour, eggs and essence vanilla

6. Pour the dough into the baking pan

7. Put the pan into the oven

8. End

Algorithm in Real Life


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Divide and Conquer Strategy

in Algorithm

Problem:Prepare a Breakfast

1. Start

2. Prepare a Breakfast

3. End


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1. Start

2. Prepare a Breakfast2.1 Prepare a tuna sandwich

2.2 Prepare some chips

2.3 Make a cup of coffee3. End


in Algorithm


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1. Start


2.1 Prepare a tuna sandwich2.1.1 Take 2 slices of bread

2.1.2 Prepare tuna paste

2.2 Prepare some chips2.3 Make a cup of coffee

3. End


in Algorithm


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1. Start


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 slices2.2.2 Fry the potatoes

2.3 Make a cup of coffee

3. End


in Algorithm


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1. Start


2.1. Prepare a tuna sandwich

2.1.1 Take 2 slices of bread2.1.2 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 coffee

3. End


in Algorithm


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What is the connection

between these real life

processes and

algorithm?

Something to ponder


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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 problemsolution

Algorithm


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Flowchart represents

algorithm graphically.

It is intended forcommunication and

documentation

Flowchart


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FlowchartBasic Syntax

Start/End

Symbol Semantic

Process

Input/Output

Test

Connector

Flow of activities


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FlowchartOther Syntax

Function call

Symbol Semantic

Magnetic Disc

Stored Data

Document/File

Multiple Document/File


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Are the steps in the

algorithm discussedearlier specific

enough to be

executed by

computer?

Something to ponder


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Problem Solving Process

Input Process Output


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Example 1Calculate and display the price of a

number of apples if the quantity in kg and

price per kg are given.

QuantityPrice_per_kg

PricePrice = Quantity * Price_per_kg



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Flowchart: Calculate Price of

ApplesInput

Quantity

Start

Price Quantity * Price_per_kg

InputPrice_per_kg

Output

Price

End


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void main() {

scanf(%d,&quantity);

scanf(%d,&price_per_kg);

price = quantity*price_per_kg;

printf(%d, price);

}

Input

Quantity

Start

Price Quantity * Price_per_kg

InputPrice_per_kg

Output

Price

End

C Program: Calculate Price of Apples


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void main() {




printf(%d, price);

}


Its not complete!

Declare the variables


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void main() {

int quantity, price_per_kg, price;




printf(%d, price);

}

Well done ! Butwhat

are they?



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void main() {


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


printf(%d, price);

}

Start Declaration

} InputProcess

OutputEnd



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Chapter 4

} Chapter 5Chapter 6

Chapter 5


void main() {


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


printf(%d, price);

}


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Example 2A car park has the following charges:

The 1sthour costs RM2.00. The subsequent hours

cost RM1.00 per hour. Write an algorithm based on

a vehicles entry and exit time.

Entry_time

Exit_time

Charge????



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Flowchart: Calculate Car Park

Charge Input Entry_timeInput Exit_time

Start

Output

Charge

End

Period Exit_time

Entry_time

Period > 1?Yes

Charge 2 + (Period * 1)Charge 2No


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scanf(%d%d,&entry_time,&exit_time);

period = exit_timeentry_time;

Input Entry_time

Input Exit_time

Start

Output

Charge

End

Period Exit_time

Entry_time

Period > 1?Yes

Charge 2 + (Period * 1)Charge 2No

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

else

charge = 2;

printf(%d,charge);

Flowchart: Calculate Car Park

Charge


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void main() {

int entry_time, exit_time, period, charge;

scanf(%d%d,&entry_time,&exit_time);

period = exit_timeentry_time;

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

elsecharge = 2;

printf(%d,charge);

}

}Chapter 7

C Program: Calculate Car Park

Charge


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Write a program to calculate the average

mark of three TK1913s students.

Example 3

Mark A

Mark B

Mark C

Average_mark

????


THINK!!


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Identify the input and output of the problem.

If necessary, use Divide & Conquer strategy

to decompose the problem into smaller andmanageable 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

Guidelines


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What might be the

disadvantage of

flowchart?

Something to ponder


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An outline of a program, written in a form thatcan easily be converted into real programmingstatements. It resembles the actual program thatwill be implemented later. However, it cannot

be compiled nor executed.

Pseudocode normally codes the followingactions:

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

Pseudocode


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1. Start

2. Read quantity

3. Read price_per_kg

4.pricequantity* price_per_kg

5. Print price

6. End

Example of Pseudocode


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Guidelines on Writing

Pseudocode

Refer to the handoutsin your manual . OK??


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CFlow Demonstration


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End of Lecture 2

Yes !! Thats all?Whats next???

INTRODUCTION TO Con the way

slide 02 - algorithm

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