1st stage: Online untimed test, given a piece of code and have to explain what it does, identify the bugs, and then provide a more efficient implementation. Short numerical reasoning question where you have to provide the correct inputs to return the right output in a program. Final part was on use cases for a program, very simple. 2nd stage: Phone interview where they go through the test only. If your code is not perfect, the interviewer will try to guide you into a more optimal solution and see if you can figure out how to make it more efficient. Unfortunately I slipped up here and wasn't able to provide a more efficient solution despite the hints. In hindsight, the problem was very simple. I think the interview was strange, but reasonable. The interviewer

The interview was very laid back and the interviewers were super nice. They would ask questions and give you hints to find the answer if needed. The first round was a coding assignment in C++ which was sent to me an hour after I applied for the job. The test was similar to what others have described: telling what a function does, finding bugs, code optimisation, use cases, etc. Then, a phone interview was scheduled for discussing my answers. At the final stage, I had a 3 hours interview in Belfast office. I was asked basic questions about Python, Numpy, Git, Linux, and Machine Learning followed by some behavioural questions. Finally, we had a lunch together. I really enjoyed the friendly manner of the interviewers and the prompt responses after each interview stage (less than a week). I asked for feedback after getting rejected for the position and received some helpful feedback from them.