TopCoder SRM 666 happened very early on Wednesday (problems, results, top 5 on the left). Zxqfl won this round despite tough competition that included two coders with "target" rating yeputons and Endagorion - congratulations!

The easy problem in this round was a nice graph theory exercise. You're given a tree and one vertex of the tree is selected. What's the maximum number of different vertices a walk of length L starting from the given vertex can visit?

Codeforces Round 318 ("RussianCodeCup Thanks-Round") took place on Saturday (problems, results, top 5 on the left). Marcin_smu has claimed the first place thanks to a solution to problem E that managed to pass the system tests - congratulations! In the post-match discussion it turned out that both passing solutions for problem E were not intended to pass: Marcin's solution gave a wrong answer on some inputs, and the only other passing solution from logicmachine relied on SIMD CPU instructions to speed up a O(n^2) solution, while the intended complexity was O(n*sqrt(n)).

While both issues could probably be avoided by investing more effort into the round preparation, I think they actually highlight one of the main good aspects of competitive algorithmic programming: it's extremely objective. Every solution is judged against the same testcases, under the same time and memory limits, and completely automatically.

Thanks for reading, and check back next week!

The easy problem in this round was a nice graph theory exercise. You're given a tree and one vertex of the tree is selected. What's the maximum number of different vertices a walk of length L starting from the given vertex can visit?

Codeforces Round 318 ("RussianCodeCup Thanks-Round") took place on Saturday (problems, results, top 5 on the left). Marcin_smu has claimed the first place thanks to a solution to problem E that managed to pass the system tests - congratulations! In the post-match discussion it turned out that both passing solutions for problem E were not intended to pass: Marcin's solution gave a wrong answer on some inputs, and the only other passing solution from logicmachine relied on SIMD CPU instructions to speed up a O(n^2) solution, while the intended complexity was O(n*sqrt(n)).

While both issues could probably be avoided by investing more effort into the round preparation, I think they actually highlight one of the main good aspects of competitive algorithmic programming: it's extremely objective. Every solution is judged against the same testcases, under the same time and memory limits, and completely automatically.

Thanks for reading, and check back next week!