My Google Coding Interview Question

At Google I’ve done over 200 interviews and evaluated over 50 hiring packets. One thing is clear, and that interviewing is hard. Signals are all over the place. Both the interviewer and interviewee have less than one hour to do their best. Sometimes, for any number of reasons, we get false or inaccurate signals. This is the nature of human beings.

Over the years, I’ve settled on a single coding question that I like a lot. It’s a sneaky simple yet difficult question. The solution is no more than 30 lines of code, but gives me the signals I need to recommend a proper evaluation. The question also scales well from interns to senior engineers. I’m not trying to say my question is better than yours, but to explain why my question helps me as an interviewer, and what I look for in a coding interview.

There will be things that you may not agree with in this article. It’s okay. These are just my opinions, and as I’m retired, I’m no longer endangering interviewees or Google engineering with hiring decisions! ;-)

Pre Script

When I was a younger engineer, I regularly read joelonsoftware.com. One article that left an impression on me was his guide to interviewing. The most important decision you can make, in less than one hour, is hire or no hire, based on whether they are smart and can get things done. Does the…