[fencepost]

Simple, fundamental, and for a surprisingly large percentage of folks completely non-relevant to anything they've done in the past 5-10 years (or more).

My immediate thought is that if I have to implement a breadth-first search from scratch it probably means that I or someone has made a terrible mistake someplace.

Also, I'd want more information. Am I just getting some values then doing some recursion? How large is the maze? The stack? Are these spherical frictionless chickens or do I need to worry about real-world constraints?

Or for someone else's mention of the Nth from last item in a linked list, my first questions would be "Do I know the length?", "Is this going to need to be repeated?" and possibly "Do I have enough RAM available to create a ring buffer of N addresses?"