What makes two recursive calls per call explode exponentially, and why does generating all subsets cost n times 2 to the n?
Short drills on what this video just taught. Write the code, run the checks, and reveal the answer only if you are stuck.
The video's fib_recur(6) makes 25 calls in all, counting the top call itself. Write a recursive function that returns how many calls fib_recur(n) makes, without computing any Fibonacci values: a base case (n is 0 or 1) is a single call, and any other call is itself plus every call its two recursive calls make. Define fib_calls(n).