[IgorPartola]

A Bloom filter would be a way more fun solution. But I think the quiet part of this is that people conducting interviews just like to feel clever in knowing some puzzle and its answer. Make them feel good about their puzzle and they like you that much more as a candidate.

My favorite way to interview people is to ask them about their work and personal projects and about what parts of those were tricky, why, and how they solved those challenges. This gets candidates to talk much more openly about what experience they have and we can discuss real world practical problems down to having them show pseudo code (or showing off their GitHub repos of specific projects) that can very efficiently tell you how they think. It’s the equivalent of “tell me about bridges you have designed” vs “here are popsicle sticks, design a toy bridge” approach.