I feel like the moral of this is to be better at cheating. I mean, if the interviewee hadn’t cheated, he still would have gotten the esoteric sorting question

I feel like the moral of this is to be better at cheating. I mean, if the interviewee hadn’t cheated, he still would have gotten the esoteric sorting question wrong, and probably failed the interview because another person had happened to remember the esoteric sorting question. So it was really a situation where there was (aside from ethical considerations) no incentive to not cheat. If it were a situation where we were evaluating the candidate based on actual work related skills, this wouldn’t be an issue. Interviewer could develop a conversation with the candidate and have an interesting discussion about the problem that will give insight into how smart they are and if they can hack it. That could have been done in this case as well, but instead of giving useful guidance, (“what if you thought about them as strings”) interviewer gave a meaningless clue. That is really just restating the problem parameters and has little to do with the implementation.