Codeforces Round #172 will take place on Sunday, March 10th at 19:30 MSK(23:30 CST).
This is my second time participating in prepration a Codeforces Round. Last time assist with YuukaKazami is an unforgettable experience. This time, the hardest problems were created by Jiatai Huang(CMHJT) and others by me and Yuping Luo(roosephu).
We gratefully acknowledge Gerald Agapov(Gerald) for his help in giving advise about the problems, Delinur for her help in translating the problems to Russian, and MikeMirzayanov, who has designed such a powerful platform.
Here let me express my personal thanks to the Codeforces community, which has given me so much gleamy idea in the past two years.
Believe it or not, Codeforces has kept her feet in China's ACM community since last year. AFAIK, some of the hardest problems have been used as this year's Winter Camp homework for our National Olympiad in Informatics.
500 — 1000 — 1500 — 2000 — 2500.
We are going to use a standard score distribution in both divisions.
The problemset is a little bit easier than last time, but we still believe, getting all of those five problems accepeted will be a challenging mission even for an seasoned International Grandmaster. The problemset has been marriaged with variety flavor. Take a glance over all five problems before going to coding might be a wise strategy.
The contest is over, congratulations to the winners:
Congratulation to tclsm2012, who also solve the problem D!
We feel so pity to al13n, your last optimization for problem D is wrong. Problem D has a O(mklogn) algorithm. And we are extremely sorry to Jacob, your solution for problem E can pass most of the random tests but actually is wrong.
Jacob... can you explain your solution for us :)
We need collect some feedback about this round .. So the editorial will appear after a period of time.
I used to hate those guys who set problems, but didn't write editorial at all! But when things turn to myself, I found it is really difficult to cover all cases. Anyway, it has been done.