Uber Software Engineer interview questions

I had a screening interview. Was supposed to have 2 interviews, but 1 decided not to join (we waited for him). Looks like I got a trainee as my interviewer, he was unexperienced and the way for him to "hint" at the solution was not what I would expect.

After the first interview, a lot of time passed and I thought they wouldn't reach out again but they did. The interview was rather difficult, but I admit I was probably umprepared.