Yes it is routinely used as a way to humiliate candidates, because it's a perfect brain teaser: Devilishly simple but difficult to conjure unless you've seen it

Yes it is routinely used as a way to humiliate candidates, because it's a perfect brain teaser: Devilishly simple but difficult to conjure unless you've seen it before - "Why couldn't I think of that???" Most undergrad CS curriculums won't cover it. https://en.wikipedia.org/wiki/Cycle_detection#Floyd's_tortoise_and_hare https://en.wikipedia.org/wiki/Cycle_detection#Floyd's_tortoi...