The easiest way to paint yourself into a corner on a technical interview question - especially a trick one - is to answer it without asking clarifying questions about boundary conditions, usage patterns, data set sizes, target hardware, etc.
and if you didn't know this going into an interview, you probably had no business going in the first place.
It's not a trick question, it's as much a part of quality software development to ask the right questions as it is to start hacking on the keyboard. The right answer to any interview question starts with "it depends, ..."
The easiest way to paint yourself into a corner on a technical interview question - especially a trick one - is to answer it without asking clarifying questions about boundary conditions, usage patterns, data set sizes, target hardware, etc.