If you just know the lookup times of various data structures, The problem isn't knowing complexity, but rather with expecting someone to code something elabora

If you just know the lookup times of various data structures, The problem isn't knowing complexity, but rather with expecting someone to code something elaborate from memory while being timed, watched, and judged by a stranger. "Code a Fibonacci heap right now, live, with no references. Begin." Nobody is arguing you shouldn't know the complexity of everything off the top of your head. You absolutely should [1], but you should also be able to figure it out pretty quickly if you don't know it. That means understanding what lg n means and understand what 2^n means, etc. (Yes, we're agreeing here, I'm just reiterating.) [1]: http://bigocheatsheet.com http://bigocheatsheet.com