9.1. Into reverse: Can you program a reverse() function, but implement it in a recursive fashion? Obviously, the best way to go about this would be using the standard string reverse() method, as detailed in https://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. At each time you raise your foot, you may opt to 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 taking one step at a time
- Always taking two steps at a time
- Taking two steps first, then one, and then one
- Taking one step first, then two, and then one
- Taking one step first, then another one, and finishing with two
9.3...