SD Squared interview questions

The interview was supposed to start at 1.30 but the interviewer came at 1.35 and 5 minutes took to settle up as there was some connection problem at his end. He gave me the problem statement and didn't explain it because as per him it is a very common interview question and there is no need for explanation. I tried 2-3 solutions that were not correct and he was giving the reason of incorrect so this way I was understanding the problem but after 20 mins he said he is running out of time and done with the interview.