The 'code challenge' is a waste of time and possibly a scam. Your application gets automatically rejected based on the result of shady automated tests with unclear requirements and without any feedback provided to you. You have 9 hours to solve the problem, I solved it in 3 and tested it thoroughly to make sure that it works correctly. After I submitted the solution, and I was informed by a vague message that the code doesn't fulfill one of the requirements. This particular requirement was contradicting the template code provided with the assignment and was generally nonsensical from a real-world engineering perspective. After two attempts my application was automatically rejected. I find such 'recruitment' practices lazy, unethical and disrespectful towards the effort of the candidate. In general, do not waste your time with this company because you don't want to work for a company which operates in this way. After my 'rejection' a quick internet search revealed to me that they have been giving this same 'challenge' for 7+ years and way too many people have had the same experience as me. Remember to do your research before doing any work for anyone!

After spending hours to do a test - they reject the application without even bothering providing feedback (and that despite the fact the test was well done and passing all the tests) - that is not a professional behavior and lacks respect for the time people invest in the process.