In this chapter you will learn: The concept of recursion, how to write and use recursive methods, how to determine the base case and recursion step in a recursive algorithm, how recursive method calls are handled by the system, what geometric shapes called fractals are and how to draw them using recursion. | 15 Recursion We must learn to explore all the options and possibilities that confront us in a complex and rapidly changing world. —James William Fulbright O! thou hast damnable iteration, and art indeed able to corrupt a saint. —William Shakespeare Its a poor sort of memory that only works backwards. —Lewis Carroll, Alice in Wonderland Life can only be understood backwards; but it must be lived forwards. —Soren Kierkegaard Push on—keep moving. —Thomas Morton OBJECTIVES In this chapter you will learn: The concept of recursion. How to write and use recursive methods. How to determine the base case and recursion step in a recursive algorithm. How recursive method calls are handled by the system. The differences between recursion and iteration, and when it is appropriate to use each. What geometric shapes called fractals are and how to draw them using recursion. What recursive backtracking is and why it is an effective problem-solving technique. Introduction . | 15 Recursion We must learn to explore all the options and possibilities that confront us in a complex and rapidly changing world. —James William Fulbright O! thou hast damnable iteration, and art indeed able to corrupt a saint. —William Shakespeare Its a poor sort of memory that only works backwards. —Lewis Carroll, Alice in Wonderland Life can only be understood backwards; but it must be lived forwards. —Soren Kierkegaard Push on—keep moving. —Thomas Morton OBJECTIVES In this chapter you will learn: The concept of recursion. How to write and use recursive methods. How to determine the base case and recursion step in a recursive algorithm. How recursive method calls are handled by the system. The differences between recursion and iteration, and when it is appropriate to use each. What geometric shapes called fractals are and how to draw them using recursion. What recursive backtracking is and why it is an effective problem-solving technique. Introduction Recursion Concepts Example Using Recursion: Factorials Example Using Recursion: Fibonacci Series Recursion and the Method Call Stack Recursion vs. Iteration Towers of Hanoi Fractals Recursive Backtracking Wrap-Up Internet and Web Resources Introduction Earlier programs structured as methods that call one another in a disciplined, hierarchical manner Recursive methods Call themselves Useful for some problems to define a method to call itself Can be called directly or indirectly through another method Fig. | Summary of the 32 recursion examples and exercises in this text. (Part 1 of 2) Fig. | Summary of the 32 recursion examples and exercises in this text. (Part 2 of 2) Recursion Concepts Recursive problem-solving elements Base case Recursive method capable of solving only simplest case—the base case If method is called with base case, method returns result If method is called with more .
