So, recently this question (on which I have the only answer) has been bumped and as a result I have noticed several upvotes coming in on my answer.
Today I received some downvotes, and as a result became aware that the question has been marked as off topic. The reason given is that it has "no objective winning criterion" when in fact it does have one:
The winner will be the person who first posts a program which accomplishes all of the following
As such it is a "fastest gun in the west challenge." I looked to see what the consensus was on Meta, and the most relevant post Are pure programming puzzles on topic? shows divided opinions on whether such challenges are off topic - in fact there is a slight leaning towards them being on topic, though not the best choice of winning criterion.
Clearly the OP of the Schlafi challenge recognised that significant time would be required to answer this question, and thought that fastest gun in the west was the best fit.
The current situation, however, is that the "winner" is already decided and this is claimed to discourage further entries. But the action taken today (closing the question) does nothing to address this issue as it now completely prevents further entries! This is especially true as the OP of the question is not particularly active on PPCG.
So, I have two questions:
Are those pure programming puzzles which take a significant amount of time to answer on topic? It's clear that the OP thought completing the challenge at all was sufficient achievement to award the acceptance (and there are a number of similar questions around.)
What should we do with this question now?
a) Leaving it closed achieves nothing.
b) Should it be reopened without editing?
c) Should it be reopened with different winning criteria, what should they be and is the OP the only person who can choose? I would welcome an answer more mathematically elegant than my own (and assume that's the kind of answer the OP would like to see) but that wouldn't likely be achieved by setting code-golf as the winning criterion. So what else? In order to encourage mathematically elegant answers, dare I suggest popularity contest? (ducks and runs for cover...)
As an aside, the behaviour of punishing the answerer with downvotes for an issue with the question seems somewhat irrational to me, but it's not a big deal, and did alert me to the fact that the question had been closed.
Per Peter's answer, it seems I misinterpreted the meaning of "pure programming puzzles". I did search the whole of meta for "fastest gun", read quite a bit (rather quickly) and didn't find anything else relevant, so wasn't sure where to look for whether fastest gun is an on/off topic winning criterion for questions such as this one (though of course I understand why it is not a good winning criterion.) Peter's link is indeed more relevant.