Beginning Algorithms (Wrox Beginning Guides)

591 Pages·2006·9.24 MB·English

by  Simon Harris

TEAM LinG
01_596748 ffirs.qxd 9/23/05 2:42 PM Page i
Beginning Algorithms
01_596748 ffirs.qxd 9/23/05 2:42 PM Page ii
01_596748 ffirs.qxd 9/23/05 2:42 PM Page iii
Beginning Algorithms
Simon Harris and James Ross
01_596748 ffirs.qxd 9/23/05 2:42 PM Page iv
Beginning Algorithms
Published by
Wiley Publishing, Inc.
10475 Crosspoint Boulevard
Indianapolis, IN 46256
www.wiley.com
Published 2006 by Wiley Publishing, Inc., Indianapolis, Indiana
Published simultaneously in Canada
ISBN-13: 978-0-7645- 9674-2
ISBN-10: 0-7645-9674-8
Manufactured in the United States of America
10 9 8 7 6 5 4 3 2 1
1MA/RS/RQ/QV/IN
Library of Congress Cataloging-in-Publication Data:
Harris, Simon, 1972-
Beginning algorithms / Simon Harris and James Ross.
p. cm.
Includes index.
ISBN-13: 978-0-7645-9674-2 (paper/website)
ISBN-10: 0-7645-9674-8 (paper/website)
1. Computer algorithms. I. Ross, James, 1968- II. Title.
QA76.9.A43H376 2005
005.1--dc22
2005022374
No part of this publication may be reproduced, stored in a retrieval system or transmitted in any form or by any
means, electronic, mechanical, photocopying, recording, scanning or otherwise, except as permitted under Sections
107 or 108 of the 1976 United States Copyright Act, without either the prior written permission of the Publisher, or
authorization through payment of the appropriate per-copy fee to the Copyright Clearance Center, 222 Rosewood
Drive, Danvers, MA01923, [phone], fax [phone]. Requests to the Publisher for permission should be
addressed to the Legal Department, Wiley Publishing, Inc., 10475 Crosspoint Blvd., Indianapolis, IN 46256, (317)
572-3447, fax [phone], or online at http://www.wiley.com/go/permissions.
LIMIT OF LIABILITY/DISCLAIMER OF WARRANTY: THE PUBLISHER AND THE AUTHOR MAKE NO REP-
RESENTATIONS OR WARRANTIES WITH RESPECT TO THE ACCURACYOR COMPLETENESS OF THE CON-
TENTS OF THIS WORK AND SPECIFICALLY DISCLAIM ALL WARRANTIES, INCLUDING WITHOUT
LIMITATION WARRANTIES OF FITNESS FOR APARTICULAR PURPOSE. NO WARRANTY MAY BE CRE-
ATED OR EXTENDED BYSALES OR PROMOTIONALMATERIALS. THE ADVICE AND STRATEGIES CON-
TAINED HEREIN MAY NOT BE SUITABLE FOR EVERY SITUATION. THIS WORK IS SOLD WITH THE
UNDERSTANDING THAT THE PUBLISHER IS NOT ENGAGED IN RENDERING LEGAL, ACCOUNTING, OR
OTHER PROFESSIONALSERVICES. IF PROFESSIONALASSISTANCE IS REQUIRED, THE SERVICES OF A
COMPETENT PROFESSIONAL PERSON SHOULD BE SOUGHT. NEITHER THE PUBLISHER NOR THE
AUTHOR SHALLBE LIABLE FOR DAMAGES ARISING HEREFROM. THE FACT THAT AN ORGANIZATION
OR WEBSITE IS REFERRED TO IN THIS WORK AS ACITATION AND/OR APOTENTIALSOURCE OF FUR-
THER INFORMATION DOES NOT MEAN THAT THE AUTHOR OR THE PUBLISHER ENDORSES THE INFOR-
MATION THE ORGANIZATION OR WEBSITE MAY PROVIDE OR RECOMMENDATIONS IT MAY MAKE.
FURTHER, READERS SHOULD BE AWARE THAT INTERNET WEBSITES LISTED IN THIS WORK MAYHAVE
CHANGED OR DISAPPEARED BETWEEN WHEN THIS WORK WAS WRITTEN AND WHEN IT IS READ.
For general information on our other products and services please contact our Customer Care Department within
the United States at [phone], outside the United States at [phone] or fax [phone].
Trademarks:Wiley, the Wiley logo, Wrox, the Wrox logo, Programmer to Programmer, and related trade dress are
trademarks or registered trademarks of John Wiley & Sons, Inc. and/or its affiliates, in the United States and other
countries, and may not be used without written permission. All other trademarks are the property of their respec-
tive owners. Wiley Publishing, Inc., is not associated with any product or vendor mentioned in this book.
Wiley also publishes its books in a variety of electronic formats. Some content that appears in print may not be
available in electronic books.
01_596748 ffirs.qxd 9/23/05 2:42 PM Page v
Credits
Executive Editor Project Coordinators
Carol Long Erin Smith
Ryan Steffen
Consulting Editor
Jon Eaves Media Development Specialists
Angela Denny
Development Editors Kit Malone
Ami Frank Sullivan Travis Silvers
Sydney Jones
Graphics and Production Specialists
Production Editor Jonelle Burns
William A. Barton Lauren Goddard
Denny Hager
Copy Editor Joyce Haughey
Luann Rouff Jennifer Heleine
Barbara Moore
Editorial Manager Melanee Prendergast
Mary Beth Wakefield Alicia South
Production Manager Quality Control Technicians
Tim Tate John Greenough
Leeann Harney
Vice President & Executive Group Publisher
Richard Swadley Proofreading
TECHBOOKS Production Services
Vice President and Executive Publisher
Joseph B. Wikert Indexing
Valerie Haynes Perry
01_596748 ffirs.qxd 9/23/05 2:42 PM Page vi
01_596748 ffirs.qxd 9/23/05 2:42 PM Page vii
About the Authors
Simon Harrisstarted writing animated sprites on a Commodore 64 in primary school. After a break of
many years, he taught himself 80x86 and IBM System/370 assembler and started working profession-
ally. Since then he has moved from assembler to C, C++, and, of course, Java. He believes a fundamental
understanding and appreciation of algorithms is essential to developing good software; and since start-
ing his own company, RedHill Consulting, he has managed to make a living discussing and demonstrat-
ing software development practices and techniques to anyone who will listen.
In his more than 15 years of development experience, James Rosshas ranged from building packaged
products to large enterprise systems to research into compilers and languages. In recent years, he has
become a code quality fanatic and agile methods specialist, particularly with test-driven development.
He works as a consultant for ThoughtWorks, the world’s leading agile software development company. He
is currently leading the development of a large J2EE project in the insurance industry in Melbourne,
Australia. He lives with his wife and family in Melbourne.
01_596748 ffirs.qxd 9/23/05 2:42 PM Page viii
01_596748 ffirs.qxd 9/23/05 2:42 PM Page ix
Acknowledgments
From Simon Harris:First and foremost, a mighty big thank-you to Jon Eaves for handing us this oppor-
tunity, and to James, whose skill and professionalism never cease to amaze me. I certainly couldn’t have
finished this book without either of you.
Many thanks also to all those who read the draft chapters and provided feedback: Andrew Harris, Andy
Trigg, Peter Barry, Michael Melia, and Darrell Deboer (I’m sure I’ve missed some). I hope you find the
final product does justice to your efforts.
I also want to acknowledge my brother Tim for listening to my ranting at all hours of the night and day,
and Kerri Rusnak and her family for feeding me waffles and cups of tea, not to mention my Aikido stu-
dents for continuing to turn up and practice during my various absences.
Finally, I’d like to extend my sincerest gratitude to everyone at Wiley who persisted with the book and
to all of my other friends and family who continued to prod and encourage me, especially when I
thought the sky was falling. It’s certainly been a learning experience.
From James Ross:First of all, I’d like to thank Simon for letting me come along for the ride on his first
book. It was a great opportunity to write seriously for the first time and it’s always a pleasure and an
education to work with Simon. We heard a lot of stories about author teams who destroy their relation-
ship while collaborating on a book, but I’m glad to say we avoided that trap.
I’d also like to thank all the folks at Wiley who were extremely understanding with two newbie
authors and guided us unerringly towards the goal—especially Ami Sullivan and Carol Long. It is
much appreciated.
To all the supergeeks at ThoughtWorks who have made my professional life such a pleasure over the
past few years, especially Andy Trigg, who’s been my programming pal since we wrote our first unit
tests together, and who reviewed all the chapters I wrote with incredible attention to detail and insight,
and Jon Eaves, the technical editor on this book, who never fails to make me laugh and teach me some-
thing. Simon Stewart also helped with great feedback on early drafts, and Gregor Hohpe and Martin
Fowler provided the encouragement and inspiration to actually keep typing all those long nights.
Speaking of the long nights, I can honestly say that this book would not have been possible (at least my
chapters!) without the love and understanding of the ladies in my life—Catherine, who is the sun in our
little solar system; Jessica; Ruby; and little Ella, who was six months old when I signed on for this project
and who slept at least 12 hours every single night while it was being written. You may never read it,
baby, but I’ll always think of you when I pick it up!