Uber's interview process was the most chaotic of the lot. First, I was set up with a completely wrong team for my interview. The interview itself went well. Some of the interviewers were clearly untrained and didn't really know what they were doing.

I did well on the interview and received an offer, but it was for another team that I had never met. This new team was working in an area more aligned with my interests. I had a couple more offers from big names, and despite this, Uber made me the lowest offer. I've heard they lowball a lot these days, which explains why they are unable to retain top talent.

The recruiter I was in touch with was unfortunately a disaster. He was constantly condescending and always acted as if he was doing me a favor. He offered a meager "$"x"" raise on stock (which is paper money anyway) and did not budge on the base salary, which was way below all my other offers. He was the most horrible recruiter I have ever encountered in my career, and I've met plenty.

I rejected the offer because I felt that Uber is full of arrogant people these days, their culture is on the decline, and they are unable to retain top talent. As the saying goes, if you pay peanuts, you'll get monkeys.

Hash map implementation already discussed in Glassdoor.