Lecture 14: Recursion

Recursion

Intro to recursion video

String example video

Optional reading: chapter 9

Note: code used in videos is available at /public/examples/chap9/.

Key ideas:

• A function that calls itself is said to be recursive.
• Problems that
  1. Have one or more simple cases with straightforward solutions
  2. Have other cases which can be redefined in terms of problems that are closer to the simple cases lend themselves well to recursive solutions.
• Basic pseudocode for recursive solutions:

  if this is a simple case
    solve it
  else
    redefine the problem using recursion
  

• We often call the simple case the base case and the other case the recursive case