### xiaowuc1's blog

By xiaowuc1, 6 weeks ago, ,

Hi all,

The third contest of the 2019-2020 USACO season will be running from February 21st to February 24th. Good luck to everyone! Please wait until the contest is over for everyone before discussing problems here.

• +127

 » 6 weeks ago, # |   +31 Excited for USACO as always! Wish everyone good luck :)
 » 6 weeks ago, # | ← Rev. 2 →   +8 Do you have an exact time when we can discuss this contest?
•  » » 6 weeks ago, # ^ |   +16 4pm UTC (11am EST) on Tuesday, if I calculated correctly.
 » 6 weeks ago, # |   +21 Has the contest finiished so that we can discuss the problems?
•  » » 6 weeks ago, # ^ |   0 now it has officially finished as it as already past 4pm UTC
 » 6 weeks ago, # |   +1 How to solve all problems in platinum?
•  » » 6 weeks ago, # ^ |   +17
 » 6 weeks ago, # | ← Rev. 2 →   +41 Notes:What's the answer for N=1 in DELEG (Plat)?O(knlogn) requires a bit of optimization to pass for HELP (Plat)?Plat sols: DELEGBinary search on K. Let dp[u] = max length path coming out of subtree u. Then, we have two cases depending on the parity of the number of children of u.Odd:We should choose one path to extend out of u and pair the other paths together. We can do this with multisets or binary search.Even: We could pair all paths together, or we could have one path end at u, have one path extend out of u, and pair all other paths together. The way to choose the path to extend out of u is similar to the odd case. TRIANGLESWLOG, x1
•  » » 6 weeks ago, # ^ |   +23 'Trash'The video is private I think
•  » » » 6 weeks ago, # ^ |   0 I think that a lot of people AKed much faster than I did, for example you can look at 300iq's screencast where he AKs in 1:23
•  » » » » 6 weeks ago, # ^ |   +4 Totally unrelated questionWhat is AK?
•  » » » » » 6 weeks ago, # ^ |   +1 AK is when someone solves all of the problemsAK = All Kill?
•  » » » » » » 6 weeks ago, # ^ |   0 Ohh thanksCan you also share link to 300iq's Screencast?
•  » » » » » » » 6 weeks ago, # ^ |   +8 I have no idea where it is, he only mentioned it to me :/
•  » » » » » » 5 weeks ago, # ^ |   0 All Killed exactly
•  » » 6 weeks ago, # ^ |   +16 "What's the answer for N=1 in DELEG (Plat)?"Clearly it should be INT_MAX :D
•  » » » 6 weeks ago, # ^ |   +43 unbovine behaviour
•  » » 5 weeks ago, # ^ |   +10 For DELEG: For the root, you can simply ignore the circumstance of dp[root] = 0 if you pick a leave as root.
 » 5 weeks ago, # |   0 How to solve problem HELP(gold)?
•  » » 5 weeks ago, # ^ |   +3 Answer = ∑ ( 2^(n-1-the number of the segments which cover l[i] ) ) Use segment tree you can pass in O(nlogn).But I don't how to solve HELP in Plat with this Idea.
•  » » 5 weeks ago, # ^ | ← Rev. 2 →   0 Use expected values and then sweepline to pass all test cases, so no need to do segment tree.
 » 5 weeks ago, # | ← Rev. 2 →   -10 I think problem P1 is particularly similar to China's NOIP2018 D1T3.
 » 5 weeks ago, # |   0 Will 710.4 be enough to pass gold?
•  » » 5 weeks ago, # ^ |   +9 Im guessing cutoff is not going to be like 750+, since 2 of the problems were kind of hard. But honestly, it seems like contestants are getting smarter nowadays so it is quite difficult to predict.
•  » » » 5 weeks ago, # ^ |   +5 I think this month's cutoff was similar to last month's difficulty so I'm crossing my fingers that cutoff will be the same. By the way, how many days does it usually take for the results to come out?
 » 5 weeks ago, # |   +58 When will USACO be releasing results?
•  » » 5 weeks ago, # ^ |   -6 I think it would be around 5 days from now. Last month was 10 (maybe? I don't remember exactly) days after the contest, anyways.
•  » » 5 weeks ago, # ^ | ← Rev. 2 →   +18 Results are out!
•  » » » 5 weeks ago, # ^ |   +21 800?... T_T