Problem A~E: The problems themselves are good and typical A~E. Indeed I like problem D. The pretest for A is a bit weak, and it's not a big problem yet.
Problem F: The problem has an origin. :) See the link: click. The problem in contest is only a weakened version of the one in Luogu.
Problem G: It's said that our great coordinator had not proved the time complexity of the intended solution is correct :) If the authors did, please share it in the editorial. (although this problem is completely beyond my ability :) )
Problem H: Oh dear 74TrAkToR, could you please OEIS the sequence before you use the "several-integer-input" problem in rounds next time? Anyone who copied the first example and opened https://oeis.org/A286331 could quickly get the formula. And the problem itself is not so hard imo. Anyway, it should not be used in contest, especially for the last problem.
For me personally, I won't participate in 74TrAkToR rounds any more. The quality of his rounds is far below the average of CF Rounds. This great coordinator has coordinated the following rounds:
- Codeforces Round 907 (Div. 2), which has a *2000 problem as Div2F :)
- Codeforces Round 880 (Div. 1 & 2), which got 1400+ downvotes :)
- Codeforces Round XXX, which has a NP-Hard problem as Div2C with intended solution in O(n log n) :)
- ...
Dear Mike:
I advise making the round unrated.
You, of course, are shocked. You, of course, think that the round should be rated.
I was also an author of a previous official round. I completely understand the efforts the authors and coordinators paid behind a round. But it is not an excuse to evade responsibility. Serious problems appeared in today's round, in problem F&G&H, ALL OF LAST THREE problems in the contest. According to testers, this round even consists of an unproven problem. If this round remains rated, I guess it will be a decrease in programmers' trust in Codeforces. To avoid this, I kindly advise you to unrate this round and assign at least 2 coordinators for 74TrAkToR rounds in the future.
Please do not reply a "You're wrong, here's why" again!
Edit: I've saved this entry locally to avoid 74TrAkToR from deleting it. 74TrAkToR has done similar things on the announcement of his rounds before. Why can he delete these comments that criticize him?
Edit2: According to testers, the MCS of problem G is wrong, now it is not an unproven problem any more :)
Edit3: I've looked at 74's appeal. Unfortunately, he did not reply to anything that was mentioned in my entry. He just said, "it's all history". :)
**Edit4: ** According to Appeal. 74TrAkToR,
We asked problem H from other authors and, unfortunately, it turned out to be known.
Is it pointing out that 74 knows that H is known, and still use it in the round?
