How to Pass a Programming Interview

Many (most?) times you provide samples for a software engineer job, they don't get looked at or serve to provide much help to your cause. That you have samples seems to help get an interview but after that it's at if the samples were never even provided. I link to many samples right from my resume so interviewers don't have to depend on HR or whoever passing on extra files. I've often asked the interviewers, "just curious, what did you think of my samples?" Almost without exception they say sheepishly say something like "sorry, didn't have time..." Which is probably true but geez you'd think a portfolio would matter more and merit a required look.

On a related note, I love the story about the Homebrew guy getting rejected by Apple because he couldn't invert a tree or some such thing. Even if it was sensationalized (or plain false for that matter), we aren't even surprised by headlines like that anymore given the current interview climate.

I'm pretty sure I could never get an engineering job at companies that interview like this. I've shipped tons of real world products over the last 20 years, founded companies, and just reading about what it is like to interview scares the shit out of me. I'm a firm believer in proving real world skills, not silly/irrelevant high pressure short time domain stuff.

Safe to say, we don't interview with whiteboard hazing. We do a phone screen mainly for personality and to see if the candidate deeply knows about a project they recently worked on. We dig in a bit there and look for the spark of passion. Then, if we are moving forward, we give a take-home project in a private git repo that is relevant to the role and tell them to spend 4-8 hours on it depending on their availability and ask them to time it and be honest. They choose the scope of work they want to accomplish. If the code looks reasonable we have a video conference where we do a code review and dive deep and ask "why" a lot.

We have been really surprised at the difference in quality of these take home projects. Some people can barely get started and struggle to produce anything. Others build full on, useful, applications.

Obviously we are screening for people that are self-starters, so being able to choose scope and regulate and make larger decisions is important to us.

An example project for a full stack c# developer:

Feel free to search around and work on the challenges as if you were on the job. Let me know when you think you can have this stuff done by. Please do this on your own time, with your own equipment and tools, and not your employer's. We don't want any lawsuits or IP ownership questions. Also, for the code, you can retain copyright if it's something you'd like to publish on GitHub, etc.

Clever Code Can you send me a code snippet in the language of your choice of something you have done that solves a hard problem in an elegant way?

For instance, here's one of my snippets from a few years back. It solves the complex problem of transactional optimistic concurrency control using ~30 lines of code. The usage of lambda expressions in C# and generics makes it succinct and expressive.

http://blog.jdconley.com/2009/01/functional-optimistic-concu...

Production Backend Question Let's say I have a very popular consumer facing service with 10 load balanced front end web servers running the latest asp.net mvc and averaging 100 simultaneous requests each, appropriately sized ms-sql servers, and a heavily used memcached cluster of 4. Everything is running great until we do some capacity planning and double the number of web servers to 20 and experience a 25% increase in simultaneous requests. Suddenly load shoots up on the ms-sql tier with far more transactions per web request than typical, overwhelming a ms-sql cluster that should have handled twice as much web traffic. Web server requests start timing out and throwing 500 errors to the clients, and the system practically comes to a halt. There were no code changes. Describe how you would troubleshoot this and what you think might be a few likely causes.

Failure Tell me about a project you have worked on that failed. What was your role? Why did it fail?

The Challenge This is meant to be a practical exercise, and is representative of the types of challenges we face. We want to see if you can make reasonable product choices under time pressure as well as write code. You get a lot of ownership here. Please use any frameworks/services/etc you want. We suggest using something you know very well. Feel free to search Google, go to the library, call a friend, or whatever you need for research. Please write all the code/copy/etc yourself. The output can run on whatever OS or PaaS/SaaS provider(s) you want, but it should be something we can also easily run. Please try to limit this to 4-8 hours of your time.

If you want to keep the repo private, please share it with me: https://github.com/jdconley

Create a web site with the following characteristics: Make the hackathon/minimal/proof-of-concept version of some popular consumer web app that you think could use some love. Craigslist, eBay, reddit, whatever...? Site must be responsive, gracefully scaling down to smartphone resolutions and up to full screen desktop displays. It does not need to be beautiful. Supports all the way down to IE8, with appropriate feature degradation as needed. Lean toward implementing things in-browser rather than in back end code. Bonus points if you do a Show HN and your implementation makes it to page 1 on hacker news.

It should be encouraging because you're being told the truth and being spoken to like an adult for once in your life.

It's been my whole career. Yeah, I've had to go in and do the grip'n'grin interview and talk to people for a couple hours to make sure I'm not a martian or something. But every job has always come about because someone at the company either knew I was competent (from working with me in the past) or asked someone I knew who told them I was.

I've never had a job that involved whiteboarding or any sort of coding test.

Whiteboard coding doesn't necessarily have to involve guessing the algorithm - any whiteboard questions I've asked avoided doing so.

On the flip side, my experience with take home projects is that they are much more of a hazing/pressure cooker ritual - at the least, the time pressure of a Google/FB/etc. interview lasts only a half hour. Most will expect candidates to spend a huge amount of time, which many won't have if they're actively job searching, or are busy people in general - I prefer to pour that extra time into open source work, since at the least it benefits others. One company assigned a project to me once that suspiciously seemed like implementing the company's whole business model.

It doesn't take long to figure out if someone has the right skills oftentimes if you ask the right questions - candidates shouldn't be penalized for companies' ineptitude in assessing interviewees.