[anonetal]

Yes, I did know that someone did it in 5 mins, so that helped :)

I think it took me 9-10 mins in total, including testing on the provided inputs. I think I could have done it in a few mins faster 15 years ago when I competed (never made it to the Finals though). Also typically: one of the team members would immediately start coding up the first problem while others are working on the next problems, with the assumption that the first one is quite simple.