[fhood]

I was taken aback by the BFS thing at first as well, but after thinking about it, I'm not sure I would be so confident about writing one if I didn't already know the basic structure due to the 50 or so times I had to implement some version of it in college. I don't feel like I can judge because I was forced to implement most of the basic data structures and traversals so many times that I can usually re-create them based on knowing 3 or 4 steps and filling in the gaps myself. I think a lot of software engineers also had this experience, and so they expect it of others, but if nobody forced you to write a path finding algorithm inside a composite pr quad trie in college then you are at a huge disadvantage for interviews, but probably less of a disadvantage for actual practical programming.

Be honest, how many of us implement our own data structures these days? I sure don't. I just build on or use whatever version of map comes with the language 98% of the time.