These days, I'm an engineering manager at Reddit, where I lead the Advertiser Optimization team. I was recently invited by the /r/RedditEng team to share an interview problem I previously used to screen candidates. It was published here, but I've reposted it here with better formatting.
I was introduced to technical interviews when I was applying to my first tech job back in 2012. I heard the prompt, scribbled my answer on the whiteboard, answered some questions, and left, black marker dust covering my hands and clothes. At the time, the process was completely opaque to me: all I could do was anxiously wait for a response, hoping that I had met whatever criteria the interviewer had.
These days, things are a little different. When I was an engineer it was me asking the questions and judging the answers. Now that I'm a manager, it's me who receives feedback from the interviewers and decides whether or not to extend an offer. I've had a chance to experience all sides of the process, and in this post I’d like to share some of that experience.
To that end, I'm going to break down a real question that we previously asked here at Reddit until it was retired, and then I'm going to tell you how it was evaluated and why I think it's a good question. I hope you'll come away feeling more informed about and prepared for the interview process.