Hand them a small hash/dictionary {a=>1, b=>2, c=>2} Have them swap keys and values. See if they can cope with duplicates. On large hiring spree (20+ hires,

Hand them a small hash/dictionary {a=>1, b=>2, c=>2} Have them swap keys and values. See if they can cope with duplicates. On large hiring spree (20+ hires, hundreds of interviews) I would walk in, give them that in any language they wanted. Moment I saw they understood, I would let them know they passed and walk out. Let others handle the social aspects of interviews. 90% failed test or took ages to get to solution. Remaining would finish it under a minute and be confused as to why we gave them such a trivial test.