ACM-ICPC World Finals 2015 Problems [pdf]
icpc.baylor.edu
icpc.baylor.edu
https://www.quora.com/Why-do-the-top-universities-like-MIT-H...
http://en.wikipedia.org/wiki/ACM_International_Collegiate_Pr...
The time limits are quite brutal for some of the problems @ finals, most of them I'd never have a proper optimal solution for.
Also, the fact that Peking understood and solved A in just 5 minutes is crazy. Sure, I could at least do A, but they practice enormously just for these.
I just tried the brute force solution in Java, took me maybe 3-4 mins to code up and it finished with the max value of n in less than 1s.
Was that 3-4 mins from first starting to read it to finishing a solution? If so then great, but personally I would've taken 10-15 minutes because I'd be carefully reading it first and wondering why it sounds so simple.
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.