Wednesday, April 1, 2015

The interview process

Looking back - there were many times I’ve went through an interview process for different software development positions in different companies. To be more precise – there were around 20 interviews I’ve went through. Frankly saying, it doesn’t matter what kind of company you’re interviewing for – 60% of the technical questions will be very similar (of course, there are rare exceptions to this rule). And if you’ve gone through at least 5 interview processes, you probably know what to look for - how to prepare for those questions.

Why ? Because most of those questions you’ll be asked will be just formality and well known mathematical problems. It’s just a matter of filling in a checkbox whether you’ve answered a question or not – and the chances you’d be ever dealing with that kind of problem during your day to day work – are almost 0! To answer these kind of questions you’d need to just have walked over any similar problem in the past. Most of those share very similar solutions.

These 60% are the bad part of the interview process and I call – THE INTERVIEW TAX. Because you have to learn those anyway even if you won’t be dealing with anything close to those questions.

Now, let’s talk about the other 40%. Those divide into three categories:

  • Thinking questions
  • Practice questions
  • Design questions

1. Thinking questions

These may easily be unsolvable mathematical problems as well. And the interviewer is asking you the question and also ask to think loudly. This is important as what he/she wants to observe – is how you think. Or – do you think at all. I know it’s funny, but I’ve seen people just having no ideas on how to solve a problem.

On the other hand, the problem can be really simple as well – very trivial – but the discussion around it will be like building a knowledge graph: you say something, you get another question on what you said, you answer again, and again get a new question – which slowly takes you away from the original topic. These discussions can take hours (luckily the interviewer will have a schedule).

2. Practice questions

The questions here are simple coding questions in your preferred programming language (unless the company has strict requirements about the coding language). In most of the cases – even a pseudo-code will be fine. These questions are aimed to verify your coding skills – like properly handling validation, corner cases. In the end you most probably will be given also a task to write unit-tests for your code. The interviewer may have noticed a mistake in the code, and sometimes want you to catch it – so be careful to do so. If you’ll write a code and the tests you’ll write won’t handle it – that’ll be reflected negatively for you.

3. Design questions

This is my preferred topic. Unfortunately these are quite rare questions during the interview process you get asked. I believe those are the most valuable ones as those will be giving answers on how well you’ll be doing your work – if you’ll be hired.

Anyway – here you may be given some real-world problems – and you’d have to solve it – by describing a system from a high level. The system can be very small or very big – depending on the responsibilities you’re being considered for. But even on the smallest systems (a simple example is an elevator or an alarm clock) some important skills can be seen.

I hope this writing will be a good overview for one who is looking forward for an interview and also for those who host interviews – to improve their existing processes, if they fall in the 60% category.

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