Intentional Software Intern - Hourly interview questions

There are four steps to the process. I wasn't able to make it through the first interview. However, I was told that the second and third one are the technical heavy interviews and that the last one is more of an exit, and easier technical interview. The first interview was all behavioral questions and for me, was a phone call interview. The interviewer went through my transcript and asked me questions that get a grasp of what I know and how I would work in a team.

Had 3 interviews. 1st HR interview was just some basic behavioral questions. Then I had two rounds of technical interviews about CS fundamentals. I did well in the 2nd round but could not solve a weird algorithm/data structure design question in the 3rd round. I think if they ask that kind of question then the interview is a lot more based on luck (which is more or less true for all interviews). I would have given the interview an overall positive experience, but the second interview was kinda bad. After I gave a solution, the interviewer would not respond until I said "hello? are you still there" something like that. When I finally came up with a solution for that weird question but not the optimal solution, she said "good" and then when I asked her "should I optimize this solution further" she declined using a very strange line of reasoning. I would have solved that problem optimally if she did not say "good", which made me think that I've gotten the correct solution.