The Recursive Book of Recursion: Ace the Coding Interview with Python and JavaScript

331 Pages·2022·10.166 MB·English

by  Al Sweigart

THE RECURSIVE BOOK OF RECURSION

T H E R E C U R S I V E
B O O K O F
R E C U R S I O N
Ace the Coding Interview with
Python and JavaScript
by Al Sweigart
San Francisco
THE RECURSIVE BOOK OF RECURSION. Copyright © 2022 by Al Sweigart.
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First printing
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ISBN-13: 978-1-71850-202-4 (print)
ISBN-13: 978-1-71850-203-1 (ebook)
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Production Editor: Miles Bond
Developmental Editor: Frances Saux
Cover Illustrator: James L. Barry
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Technical Reviewer: Sarah Kuchinsky
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To Jack, who held up a mirror
in front of my mirror
About the Author
Al Sweigart is a software developer, fellow of the Python Software
Foundation, and author of several programming books with No Starch
Press, including the worldwide bestseller Automate the Boring Stuff with
Python. His Creative Commons licensed works are available at https://www
.inventwithpython.com.
About the Technical Reviewer
Sarah Kuchinsky, MS, is a corporate trainer and consultant. She uses
Python for a variety of applications, including health systems modeling,
game development, and task automation. Sarah is a co-founder of the
North Bay Python conference, tutorials chair for PyCon US, and lead orga-
nizer for PyLadies Silicon Valley. She holds degrees in management science
as well as in engineering and mathematics.
BRIEF CONTENTS
Foreword . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xv
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .xvii
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .xix
PART I: UNDERSTANDING RECURSION . . . . . . . . . . . . . . . . . . . . . . . . . . .1
Chapter 1: What Is Recursion? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3
Chapter 2: Recursion vs . Iteration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21
Chapter 3: Classic Recursion Algorithms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .45
Chapter 4: Backtracking and Tree Traversal Algorithms . . . . . . . . . . . . . . . . . . . . . . . . . .71
Chapter 5: Divide-and-Conquer Algorithms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .93
Chapter 6: Permutations and Combinations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .123
Chapter 7: Memoization and Dynamic Programming . . . . . . . . . . . . . . . . . . . . . . . . . . .151
Chapter 8: Tail Call Optimization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .163
Chapter 9: Drawing Fractals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .175
PART II: PROJECTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .201
Chapter 10: File Finder . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .203
Chapter 11: Maze Generator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .215
Chapter 12: Sliding-Tile Solver . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .231
Chapter 13: Fractal Art Maker . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .259
Chapter 14: Droste Maker . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .283
Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .297