specifying the types of number that the sum of the digits adds to (e.g. “the sum of the digits is a prime number”) and so on. Randomly generate a clue such that the search space is bisected (within given parameters to ensure that neither too many nor too few clues are needed) The first three clues of Claire’s puzzle are sufficient alone to reduce the search space to a single answer, although a human is likely to need more.

first and then come up with clues that describe it. Instead, though, my solution would come up with clues, apply them, and then see what’s left-over at the end. open to ideas (and if you don’t like that I’m not implementing your suggestions, you can always fork a copy of the code and change bisections only: the yellow bisection is rendered redundant by the light blue one. I’ve left this as a deliberate feature.Anyway: you should go and play the game, now, and let me know what you think. Is it worth expanding and improving? Should I leave it as it is? I’m Visualising the solver as a series of bisections of a search space got me thinking about something else: wouldn’t this be a perfectly reasonable way to programatically generate By the time I’d solved her puzzle the conventional way I was already interested in the possibility of implementing a general-case computerised solver for this kind of puzzle, so I did. Or if you’d like to see some of the other JavaScript experiments I’ve done, you might enjoy my “cheating” hangman game, my recreation of the lunar lander game I wrote in college, or rediscover that time I was ill and came up the worst conceivable tool to About three months ago, my friend Claire, in a WhatsApp group we both frequent, shared a brainteaser:

under 10 kB, most of which is the puzzles themselves (which are pregenerated and stored in a JSON file). Naturally, it lends itself well to running offline, so it’s PWA-enhanced with a cows” nomenclature, a “bull” is a correctly-guessed digit in the correct location and a “cow” is a correctly-guessed digit in the wrong location, so the puzzle’s clues are: number of different digits used in the combination, the sum of the digits of the combination, and whether or not the correct combination “ascends” or “descends”. I’ve ideas for Sometimes it comes up with inelegant or unchallenging suggestions, but for the most part my generator produces adequate puzzles. Feel free to stop scrolling at this point and solve it for yourself. Or carry on; there are no spoilers in this post.