The HR representative was very nice. First, there was a simple Hangouts call to discuss the process, then one algorithmic screening, also by Hangouts. Afterwards, I was flown to Zurich for five more interviews. These were much harder than the phone interview and included four algorithmic interviews and one about system design. Overall, I am happy with the process; it was quick and pleasant.

You have a list of matches. Each match is a pair of integers, representing (ID of Player One, ID of Player Two), where in that match Player One is better than Player Two. Make a ranking of all the players in order.