Dunno, the first time I went to Google interview I had absolutely brutal one as my first question (a complicated dynamic programming on combinatorial problem without closed form solution), and I absolutely loved it and after some discussion with the interviewer came to a solution in about 20 minutes, all on whiteboards I hate. I am not sure why wouldn't you rather use the time for interview or something more meaningful than to test if somebody can do a programming equivalent of 1+2+3 when you can observe from their CV that they probably aren't complete beginners and you are interviewing to get somebody for a very senior job.