The Elon Musk interview question | Hacker News Reader

The Elon Musk interview question

7 pointsdaly6 comments

I've interviewed. The interviews are generally what I call "clown nose" events. "WE all wear clown noses. If YOU want to work here you need to look sharp in a clown nose!"

In more concrete terms, the "clown nose" interviews these days have moved on from the "trick question" (aka "why are manholes round?") to questions on data structures. Why? Well, for the obvious reason that the initial interviews are with people who recently graduated and Data Structures was likely their last course at school.

Elon says HIS question is "What are 3 problems you've solved and how did you solve them?".

He points out that people who ACTUALLY solved the problem can describe the problem exactly and describe how they solved it in great depth. People who "sort of helped" are much less clear about that.

The brilliance of this question is that it selects for the quality he needs. He wants people who not only know how to solve problems but also know how to implement the solutions. He rewards problem solvers that implement.

Tesla is the new IBM Research / Bell Labs.

Why would you want to work anywhere else?

> Why would you want to work anywhere else?

They are not hiring where I live and I heard bad things about the work conditions so I never considered them.

Still, I really like their products but I don't think I would be a good fit as an employee. It's also hard to work for the richest man of the world, I prefer non profit organizations.

I guess because you have a life or interests outside of work. I'm pretty sure that my impression is correct and that anyone working there is not leaving at 5 to pick up their kids or going kayaking road trips at weekends with their friends. They are dedicated, smart engineers with little interest or time outside work. That's fine for them, but it doesn't work for me. I'm probably not smart enough anyway, but I'm damn sure I'm not committed enough.

1. I had a controller with 512 bytes of program store, and I need to be able to adjust timing to adjust for distances and variable line speed. I implemented an NCO, and a PLL to take pulses from one of the pullies on the belt, and was able to get everything working across a wide range of speeds and offsets, and add another feature, with 2 bytes left over. ;-)

2. I needed to allow users to edit the questions in a survey system back in the days of MS-DOS. I implemented a system where the had edit fields that matched the display on the portable computers, and then gave them 2 branches for yes/no questions... they could chain them any way they wanted, and it worked.

3. I needed to detect an infrared laser to aid in the alignment of inter-building communication links... it turns out that if you put an infrared filter over a solar cell, you can build a detector fairly cheap. I built an accompanying box to send an audio frequency sine wave into the transmitter.

4. I had a small program that searched through a megabyte of text back in the DOS days... it was deemed too slow... (30+ seconds)... I wrote a small loop that used the XLAT instruction to do a pattern match, shifting a bit through the accumulator until it got to a carry, which was a match... time was less than 3 seconds.

Yeah... bragging about accomplishments is fun

The problem as usual is that once everyone think this is a great question, it'll pop up in every article about how to prepare for an interview, and people will come with their pre-canned answers.

This is why I know why manholes are round, and what a red-black tree is (more or less)...

A friend of mine would just extend the list to get past the pre-thought answers. He'd ask: what are 8 of your weaknesses? I find it a little tough though...

Well, I ask the same kind of interview question when conducting interviews for Red Hat and work-life balance is much better ;)

None of the problems I've solved really stand out to me that I would remember them much past the time I've solved them. Same goes for most "Tell me about a time when you..." questions.

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