>Jumping in to implementing something would be a bad move.
I would expect a skilled programmer to be be able to make intelligent inferences about the intended behavior in the face of ambiguous problem statements. FWIW, I would probably explain my reasoning as I went -- would you interrupt a candidate to say you'd rather see a different behavior (ex: my prototype would return a list with an empty string, but maybe you'd rather an empty list), or just silently judge them? Also, it look me about 2 minutes to produce a reasonable prototype -- maybe if the challenge were harder I'd expect someone to ask more questions up front, but in this case it's trivial to iterate.
If the only thing you are testing for is the instinct to clarify unclear requirements, you'll surprise people who are used to the leetcode-style, thereby getting false negatives. It's just as much a trick question then, just in a different dimension.
I would expect a skilled programmer to be be able to make intelligent inferences about the intended behavior in the face of ambiguous problem statements. FWIW, I would probably explain my reasoning as I went -- would you interrupt a candidate to say you'd rather see a different behavior (ex: my prototype would return a list with an empty string, but maybe you'd rather an empty list), or just silently judge them? Also, it look me about 2 minutes to produce a reasonable prototype -- maybe if the challenge were harder I'd expect someone to ask more questions up front, but in this case it's trivial to iterate.
If the only thing you are testing for is the instinct to clarify unclear requirements, you'll surprise people who are used to the leetcode-style, thereby getting false negatives. It's just as much a trick question then, just in a different dimension.