Questions

9.1 Into reverse: Can you program a reverse(str: string) function but implement it in a recursive fashion? The best way to do this would be using the standard string reverse() method, as detailed in developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/reverse, but that wouldn’t do for a question on recursion, would it?

9.2 Climbing steps: Suppose you want to climb up a ladder with n steps. Each time you raise your foot, you may climb up one or two rungs. In how many different ways can you climb up that ladder? For example, you can climb a four-rung ladder in five different ways:

• Always take one step at a time
• Always take two steps at a time
• Take two steps first, then one, and then one
• Take one step first, then two, and then one
• Take one step first, then another one, and finish with two

9.3 Sorting recursively: Many sorting algorithms can be described with recursion; can you implement them?

• Selection...