I applied for the Reliability position because of my experience at AWS. The initial call went pretty smoothly, and it ended 25 minutes early. The questions were straightforward, involving sorting version numbers.

I was then invited for an on-site interview. Scheduling the flight was a mess. I provided my options, and they confirmed a date. However, they then presented options to fly out of the wrong airport. When I asked them to fix it, there was no reply for a few days. Upon their reply, they stated the flight had become too expensive and suggested I switch my interview to the following week. They presented this as a minor inconvenience, but I had to rearrange my schedule.

The on-site experience was also not pleasant. My first interviewer was late, so someone else had to fill in. This person had started at Uber six months prior and clearly lacked knowledge. It was awkward. He asked me questions about my prior job experience.

The next round was similar, except it was with the Architect, who asked many follow-up questions about my experience. The third round was the behavioral interview, with one of the hiring managers. They asked how I would react in various situations and inquired about my reasons for applying to Uber and this specific position.

The fourth round was the coding interview. They gave me two easy problems on HackerRank, which I completed on my own machine: the first was a probability question, and the second was a simple GET request. I solved both relatively quickly, with only minor issues loading some libraries in HackerRank.

The final question was a design question: to build a centralized configuration management system with the following constraints:

• Changes must be reviewed.
• Changes must be incrementally deployed.

I proposed using daemons as service clients and a configuration service to push changes. I also suggested blue-green deployments, a web client for team communication, and a registration process for new services. The interviewer seemed to resonate well with most of my ideas. My experience at AWS made this design challenge manageable.

After three days, I was rejected. This was for an SDE II position, and I am unsure of the exact reason.

Given 23 people in a room, there is a 50% chance that there is a pair that shares the same birthday. Write code to test this hypothesis.