A mathematics week

There were two rounds last week. TopCoder SRM 775 took place on Thursday (problems, results, top 5 on the left, analysis). Tourist has earned a commanding victory while having the fastest time on all three problems, which also meant that nobody could get the 5 points towards the TCO20 qualification. Well done :)

The main part of the hard problem was a nice puzzle that could well appear in a mathematics olympiad: for which pairs of positive integers a <= b can we split all integers from the set {a, a+1, a+2, ..., b-1, b} into two parts with equal sum?

Codeforces Round 614 followed on Sunday (problems, results, top 5 on the left, analysis). There was just one accepted solution for each of the two hardest problems, coming from Um_nik and tourist who have therefore occupied the first two places with a huge margin. Um_nik's problem was worth more points, and he had therefore won the round. Congratulations!

Thanks for reading, and check back next week!