I have a feeling that the question is not really about whiteboard coding or solving graph problems. This is a blatantly ambiguous task. Maybe it was meant to force the interviewee to demonstrate how they communicate to the interviewer that they needed more information about the problem before starting.
Pretending you understand or blindly assuming what the interviewer meant is more of a red flag to me than requiring a few rounds of clarification.
In my opinion, an ideal interviewee would communicate that they don't fully understand the requirements and possibly offer a brief set of possible interpretations. Once the interviewer has clarified, my ideal interviewee would restate the clarification to demonstrate competence and verify their new interpretation of the requirements before proceeding.
Pretending you understand or blindly assuming what the interviewer meant is more of a red flag to me than requiring a few rounds of clarification.
In my opinion, an ideal interviewee would communicate that they don't fully understand the requirements and possibly offer a brief set of possible interpretations. Once the interviewer has clarified, my ideal interviewee would restate the clarification to demonstrate competence and verify their new interpretation of the requirements before proceeding.