How to ace coding interview

Friend of mine (a senior data scientist) applied for a dream job and despite years of experience was rejected. He failed the coding part of technical interview 😱 

Not every company has this practice as a part of hiring process, at least in Germany. But if they do, it might be difficult to pass it without preparation.

Today let's discuss what are the typical types of coding skills checking for Data Scientists and Machine Learning Engineers.

↪ Coding SQL or Python in Codility or similar platform

You get list of tasks, which you need to solve within certain time (from 30 min up to 2 hours). There is only one attempt and you can't pause/resume.

🎶 Preparation: refresh SQL and Python basics, solve easy and medium level problems on Leetcode, (if available) try demo version of the platform, which company of your choice usually uses for the tests.

↪ Take Home technical case study with 3 or 7 days to finish

You are provided with a small dataset and should create some ML application with it. In addition to the code, you need to write a report and present your solution in the next round of the interview. 

🎶 Preparation: do projects on your own and always write a summary for them, seek feedback of colleagues/mentor for your project documentation and its code (Is it readable? Is it well structured, etc), be curious about Data Science application in various fields

↪ Live Case Study during interview to test your problem solving approach

Depending on the role and company the live case study can be a discussion of how you would create a solution or design an ML system. Or it can be "white board" coding live in front of your (future) colleagues.

🎶 Preparation: first of all figure out which type of interview should you expect. 

For "white board" live coding: refresh SQL and Python basics, solve easy and medium level problems on Leetcode, practice to walk through your thought process and discuss idea of the solution before you start coding.

For more theoretical "live case" discussion: do research on use cases in the company/industry you're interested in, also practice to walk through your thought process (very useful skill!), study system design and ML system design.

📞 Did you ever encountered the coding interview before? What did you do to prepare for it?