Skyscanner coding challenge

I have just been invited to do a coding challenge for Skyscanner as part of a further step in their application process for a Software Engineering New Grad position in London. They say they will test me in algorithms and data structure and that the challenge is two hours long. How should I prepare for it? What should I expect? I have 3 days to do it. P.S. I'm in my last year of a master in physics (thesis in AI) with experience in data science and have done Hacker Rank and LC for a couple of years now. TC: not disclosed but around £30k + (salaries are not great for new grads in Europe).