Guess a number

Problem: Think of a number in the range 1 to N.

Reworded:

• given a set of N possible numbers to choose from
• guess a number from the set
• if wrong, guess again.
• continue until the number is guessed successfully

Recursion comes into the "guess again" stage.

• A set of N-1 numbers remains from which to guess.
• This is a smaller version of the same problem.