"It was a sheer stroke of luck on your part,
is a much easier puzzle, because it is capable of more systematic
analysis; yet it may just happen that you will not do it in an
Romeo on a white square and make him crawl into every other white
once with the fewest possible turnings.
This time a white square may be
visited twice, but the snail must never pass a second time through the
same corner of a square nor ever enter the black squares."
"May he leave the board for refreshments?" asked
"No; he is not allowed out until he has performed