Citadel Software Engineer (PhD Graduate) interview questions

After applying I was asked to complete a programming challenge on Hackerrank. The questions were of medium difficulty. My solutions passed a majority (but not all) of the public test cases (I ran out of time). I was asked about two weeks later for a (technical) phone interview. The interview lasted approximately 45 minutes. However, the first 15-20 mins of that was spent between the interviewer and myself introducing ourselves. This only left approximately 25 mins for a programming problem. The problem itself is ranked hard on LC, and I felt it was one of those problems that if you didn't know the "trick", then coming up with it under the stress and time pressure of the interview is hard. After the interviewer gave me 1-2 hints, I was close to figuring out the optimal solution, only for the interviewer to cut me off and state we ran out of time. On the one hand, the problem itself was interesting but hard; I wish I would have had 5-10 more mins. On the other hand, I feel the interviewer should have monitored the time remaining more carefully so that my skills could be properly assessed.