structured problem solving an introduction

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PEStructured Problem SolvingAn Introduction

Stewart Blakewayblakews@hope.ac.uk0151 291 3113

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PEAims of the presentation• to quickly list the skills to be developed on

the SPS strand of the course• to officially start the course

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Skills to be developed in the SPS strand of the course

• Problem Solving Skills • Programming Skills• Team Interaction Skills• Presentation Skills• Reflective Skills

The most important bit

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Skills to be developed in the SPS strand of the module

• Problem Solving Skills • Programming Skills• Team Interaction Skills• Presentation Skills• Reflective Skills

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Problem Solving Skills

• Analysis of Problems– Crossing a busy road– Eating a Pie– Cooking a Pie– Climbing Mount Everest ??????– Getting PieEater to do something complicated– Writing other software to do something

complicated

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Problem Solving Skills

• Analysis of the Structure of Solutions– Sequence– Selection– Repetition

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Problem Solving Skills

• Structured English– Sequence– Selection– Repetition

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Skills to be developed in the SPS strand of the module

• Problem Solving Skills • Programming Skills• Team Interaction Skills• Presentation Skills• Reflective Skills

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Programming Skills

• Introduction to Java – Java Programming Constructs– Java Trainer– The PieEater

• Java revisited– Object Oriented Concepts– BlueJ Integrated Development Environment

• (http://www.bluej.org/about/what.html)

– The PieEater again plus Close Friends– Graphics and Animation

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Programming Skills

• Data Structures– Selection of Appropriate Data Structures– Sorting– Searching

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Skills to be developed in the SPS strand of the module

• Problem Solving Skills • Programming Skills• Team Interaction Skills• Presentation Skills• Reflective Skills

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Team Interaction Skills

• Animation Problems– Solved in Groups– Coded in Groups– Tested in Groups

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Skills to be developed in the SPS strand of the module

• Problem Solving Skills • Programming Skills• Team Interaction Skills• Presentation Skills• Reflective Skills

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Presentation Skills

• Presentation of Working Animations– Demonstration of the Running Animation– Explanation of the Choice of Variables– Explanation of the Algorithmic Design– Explanation of the Data Structures Selected– Discussion of Possible Enhancements

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Skills to be developed in the SPS strand of the module

• Problem Solving Skills • Programming Skills• Team Interaction Skills• Presentation Skills• Reflective Skills

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Reflective Skills

• Reflect on Team Work Activities• Reflect on the Scope of the Task• Highlight Possible Failings in the Mechanics

of the Team Work Activity• Suggest Possible Improvements to Team

Work Interaction

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Let the course begin …..

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Your First Seminar

createpieeater();pendown();walk();penup();walk();pendown();turnright();walk();walk();

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Let’s Loop-the-Loop

createpieeater();while (test)

{ actions;}

other actions;

Sequences of Actions each Ending with a Semi Colon

No Semi Colons

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Semi-colons: a working rule

• Do not put them at the end ofwhile()if (){}

• Do put them at the end of other linesint a;a = 7;turnleft();

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while (test) { }

test– clearahead– direction != “SW”– pieinsight

clearahead and pieinsight are either true or falsedirection != “SE” can be evaluated to either true

or false

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Loop Operation

while (test) { actions; }

other actions;Evaluate test

true false

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Test is True

while (test) {» actions;

}other actions;

Enter Body of LoopExecute [actions;]Evaluate test Again

Body of Loop

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Test is True

while (test) {» actions;

}other actions;

Enter Body of LoopExecute [actions;]Evaluate test Again

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Test is True

while (test) {» actions;

}other actions;

Enter Body of LoopExecute [actions;]Evaluate test Again

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You Get the Idea

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Test is False

while (test) {» actions;

}other actions;

Jump to other actions; and Continue with the Rest of the Program

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{actions;}

walk();pendown();penup();turnleft();turnright();• You add the rest

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Selection

• The if statement allows us to specify alternative actions depending upon a test

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if (test) { }else { }

if (pieinsight) { eatpie(); }else { walk(); }

Selection

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if inside a loop createpieeater();

randompies(20);while (clearahead) { if (pieinsight) { eatpie(); } else { walk(); } }

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Counting loops - for

int i;createpieeater();for (i=0; i<5; i++) { walk(); }

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In Conclusion

• Problem Solving is a Skill– Riding a Bicycle– Swimming– Keeping Awake in Lectures

• It Cannot be Learned Quickly• It Cannot be Learned without Practice• Every Failure is Part of the Learning Process

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PELecture Exercise 1• Draw the following grid

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PETrace out the following program

createpieeater();turnright();pendown();while (clearahead){walk();}

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PELecture Exercise 1 Answer

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PELecture Exercise 2• Write the program for

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PELecture Exercise 2 Answer

createpieeater();int i;for (i=1 ; i<=4 ; i++)

{ while (clearahead)

{ walk(); }

turnright(); turnright(); }

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PELecture Exercise 3 – spot the syntax error

createpieeater();int i;for (i=1 , i<=4 , i++)

{ while (clearahead)

{ walk() }

turnright(); turnright();

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In Conclusion

• Programming Languages are Merciless– Syntax Matters– Semi Colons can be Dangerous

– In Conclusion: }

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Questions?

• Next…– Problem Solving in your seminars

• More loops• If statements

– Next lecture on Algorithms– Setting of assessment next week