I wrote a five-minute answer to this while disconnected, during which time the author deleted the question. Discard my answer or undelete and post? Not a big deal to me either way.
In the rare case that one has worked up an answer, only to find the OP has deleted what seems to be a legitimate question, the possibility exists of rewriting and posting the question oneself.
The OP may have legitimate reasons for deleting, and I'd err on the side of privacy by not inquiring too closely into the reasons. The only caveat I can think of is where the question might be part of some online competition (or homework), but many times legitimate questions will be too unpolished to be that kind.
Here the circumstance turned out somewhat differently. Not everyone realizes that self-answering of questions is legitimate here, and of course my suggestion emphasizes this fact.