I agree with the other reviewer. Voleon expects very busy people ( we are talking senior level Machine Learning experts here ) to spend several hours solving a problem including writing code and a write-up of the solution. Then you send it in and basically get a yes or now answer. They don't provide any feedback whatsoever, in the name of keeping the "integrity of the process". How about trusting the integrity of your candidates? Or if that is too much to ask, have multiple variants of the problem, or change it often enough. Or just tell candidates beforehand how the process works. If I had been told I wouldn't have bothered. Overall, an unpleasant and obnoxious process. Guess they are swimming in candidates.