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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. 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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 opportunity, 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!