[tdumitrescu]

Yeah, calibrating coding questions for timed interviews is really tricky and in my experience always requires iteration. Trick questions with an "aha!" moment lead to binary outcomes (either you pass or completely flop) and don't give much useful signal. On the other hand, simplistic questions tend to focus the interviewer on critique of stylistic details and personal coding habits/preferences which don't say much about the interviewee's effectiveness.