The Magic Bean

Adventures in Interviewing

Ah, remember the era of the puzzle interview period? How many BBs fit in all the left shoes of the population of Muncie Indiana that is older than 47? Google does it, so everyone’s gotta do it.

I guess the idea was it measured some sort of ability to solve problems in the abstract. This tale is about doing just that, but I flipped the frame on the interviewer.

I was interviewing downtown Denver. I can’t remember the year, but LoDo had just started to revitalize. It was my hot PowerPC summer. My friend Scott had a cool loft apartment with a huge TV and stereo, and we listened to Led Zeppelin at absurd volume levels and ported x86 code which acted as interludes between C and FORTRAN routines to PPC as I’d managed to get a contract with the folks who design the things that go boom and they had a brand new PowerPC-based supercomputer in that brief moment when PPC SIMD was faster than Intel SIMD and they wanted to run their simulated bombs on it.

We had a 1u PowerPC “blade” server that was really a bronze keyboard PowerBook G3 motherboard in a rectangular 1u metal can that we used as a development box. It was fun, C, FORTRAN 77, and x86 and PPC assembly. It was typical research lab FORTRAN code, randomly spiced up with more “modern” C. “What does the PPC ABI say the proper register allocation is when calling a function with 9 integers and 32 float arguments and a pointer to a common block.” The story was the lab didn’t realize they had all this x86 assembly, they just expected to be able to recompile the C and FORTRAN on PPC, and when they couldn’t, they called in the expensive PPC consultants.

I really enjoyed LoDo. Prior to this they had the viaducts over many of the streets in the area, and underneath was the underworld, where street sweepers never seemed to go. It was amazingly filthy. I remember the cheapest tire store in the Denver area, where I bought tires for my ancient VW bus was under the viaduct near where I many years later ended up working for Comcast on cloud nine.

They tore out all the viaducts as part of the LoDo revitalization. There are still lots of buildings with obvious entrances that were on the viaduct level that are now bricked up. I wonder if anyone ever wonders about why there are so many of those second story doorways to nowhere.

Anyhow, I had managed to score an interview with some hot startup in the newly revitalized LoDo. I went to their cool office space with exposed brick wall and ductwork hanging from the ceiling. It was really quite cool. Man back then I got an interview at every job I applied to. Things have certainly changed.

So we got down to business. The interviewer told me they had 7 beans or 9 beans or something, I don’t remember. One bean was heavier than all the others. They wanted to know the minimum number of weighings to identify the heavy bean.

I thought about it for a while and said “three.” (I don’t remember the exact number. This is metasyntactic three, made up for the purposes of dramatization). The interviewer said “very good! How did you arrive at this number?” I replied, well, I thought of the obvious solution and it was four, but I figured you wouldn’t have asked me if there wasn’t some trick. I figured the trick would save one weighing but was unlikely to save more. So that is why I chose 3.

The interviewer looked at me. Silence settled at the table. I held his gaze and didn’t say anything. Finally, when the pause started to get uncomfortable I said “so is that what you do around here? Weigh beans? I was hoping maybe we could talk about software.”

At that point I turned the interview around, and totally ran it. Sometimes it’s good to do this, you have to read the room though. In this case it was good, by the end of the interview, everyone was excited. They told me I was in for a treat because they were working with the very latest .NET technologies.

I mean, I literally didn’t care. emacs is better than vi. tabs are better than spaces. And UNIX is certainly better than .NET. No way was I going to take that job. But I was interviewing just for the sport of it.

I don’t remember the name of the company, any of the people, or what they built, but boy do I remember the magic bean. I hope they did well, they seemed like nice people.