Authors test 1000s (a bit of exaggerated) solns, its not necessary to allow all of them to pass.

Can someone explain time complexity of 207670551?
I do not understand why its fast enough (run in <350 ms), worst case I can think of will take $$$O(n*sqrt(n))$$$.

There is a slight difference between these two problems, operations are same but arrays are cyclic in ARC problem, but they aren't in TROC problem.
So you should solve TROC problem for n different A's A[i...n]+A[0....i-1] (when B has < n distinct elements), if answer is yes for any of them, answer is yes overall.

In this example, first change B to 1 2, removing consecutive elements taking into account that array is cyclic. Then 1 1 3 2 has 1 2 as subsequence.

Submission

TROC 30 B makes today's' C trivial.
Upd: Added problem link instead.

It is just a side-affect
I just have one clarifying question. So their match is a star with 187830914 in center and you send mails to everyone in connected component?

Given your rating and your position in the final standings, I understand you are happy because of your performance in this contest. In this contest the most typical topics such as known algorithms or DP were not present as you mentioned, and I assume this is the kind of problems in which you perform the worst. However, the most common themes don't need to appear in every contest, so you shouldn't blame the coordinators for your dependence in said themes to perform at your usual level.

Your submission is $$$O(sum*\log sum)$$$

In Div 1A for test case -

1 3 1 1 1

Why is answer 0 0 0 wrong? According to the definition in problem statement 0 0 0 is larger than 0. We can obtain 0 0 0 by choosing k=1 3 times.

Upd: Nvm. Realized its correct answer. I did changed break to continue in my code before submitting..

The funny thing in this contest is sjcsjc 's template had custom_hash but still he got hacked for using c++ default hash. 131404435 After that he dropped from 4th rank to 87th rank among rated users.

Found this tree here
Just one clarification, this qualification is for regionals that are yet to be scheduled for WFs supposed to happen in June 2022? Or for the world finals supposed to happen in June 2021?
These too many parallel worlds finals plans at the same time make it really difficult to keep track of who is eligible for which WFs.

$$${1,19,19,20}$$$
Answer is 18 (1 xor 19 = 18, 19 xor 20 = 7) but removing 19 makes it (1 xor 20=21).

Thanks.
This just proves that median observation in editorial since that function is sum of signum functions derivate will change sign at median only.

ARC E -
If one didnt realises second observation in E. Then $$$LCM_{j \neq i}(A_j)$$$ can be computed in $$$O(n \log max(A_i))$$$ using prefix and suffix LCMs with bigints.
Python Submission
Time complexity $$$O(n^3 \log max(A_i))$$$ remains same.

More specifically how did I come up with this particular solution was -
Since there exists one last no from index $$$i$$$ such that $$$LCM_{j \neq i}(A_j) \neq LCM_{j}(A_j)$$$. This python solution just brute forces to find one such index which can be last. Then recursively solves for the rest of $$$n-1$$$ numbers.

Hunger strike?

First, we sort nos as given in editorial. dp[pos][left][turn] expected gold we will get if [1...pos-1] is taken by one of the parties and [pos...n] is yet to be taken. Similar to this ARC problem left is no of gold we have delayed. turn is a boolean which denotes whose turn it is.
Then we have transition states.

double dp(int pos, int left, int turn){
	if(pos == n) return 0;
	if(left > n-pos) return 0;
	if(memo[pos][left][turn]>=0) return memo[pos][left][turn];
	double ans = 0;
	if(turn == 1){
		ans = dp(pos, left+1, 1-turn);
	}
	else{
		// with probability left / (n - pos), this was taken
		double tkn = left * 1.0 / (n - (ld) pos);
		ans += tkn * dp(pos+1, left-1, turn);
		ans += (1.0 - tkn) * (a[pos] + dp(pos+1, left, 1-turn));
	}
	return (memo[pos][left][turn] = ans);
}

Similar problem — D. Two Pirates — 2

How to solve last problem?

We can prove that this strategy and "buying at minimum turning points and selling at maximum turning points" produces same result. So if one is correct other is also correct.

Simple greedy works.
"Buy stocks only if its profitable to buy today and sell tomorrow."

money:=1000
for i:=0;i+1<n;i++{
  stocks:=money/a[i]
  money+=stocks*max(a[i+1]-a[i],0)
}
Fprintln(out,money)

Can you please share your checker of BOJACK?
How does it check if a given string is valid?
Even my brute force O(n^3) checker was wrong.

P.S. — Combined round would have been better. Separate divisions exist so that div1 users arent forced to solve easier problems not the other way round.

I got a plagiarism message from System for today's div 3 (Round 644) and my submissions were first skipped and later on marked as accepted. So I guess the issue is sorted out. Anyways I will still write an explanation here.

You can check that the main function is totally different across all submissions. What common is Fast IO template in python which is available here in pyrival "A Python Library for Competitive Programming". Even better you can also check my previous submissions you will find the same fast IO template (those should be enough to prove that the "the code was written and published/distributed before the start of the round,").

"Any usage of third-party code should not violate the right holder’s license or copyright."
License for the library is "Apache License 2.0" which states that "The Apache License is a permissive free software license written by the Apache Software Foundation. It allows users to use the software for any purpose, to distribute it, to modify it, and to distribute modified versions of the software under the terms of the license, without concern for royalties."

vovuh MikeMirzayanov
I made 25 MLE hacks using pajenegod's test case which TLEed my soln 80141105 . I see ratings got updated but I can't find that test case in system tests (same soln passes 80201283).

Since ratings are updated and only 3 test cases were added in system tests.
Question 1. Is there a system testing phase in Div3? Or if nobody hacked you mean your soln is an AC.
Question 2. If there is one then why was this hack ignored?

26 solutions were hacked using this test case among 127 successful hacks in the round (more than 20%). Shouldn't this be a sufficient reason to blindly add this hack in system tests?

Just to clear confusion here. You misunderstood my last comment.
I was talking about pajenegod's submissions which you said were slow. Pajenegod's in contest submissions takes less than TL/2.
Someone wrote that slower code and asked pajenegod in AC discord server for help. He submitted that code.

Anyways let's stop this debate here. It can go long. Its completely upon you how many problems you want beginners to solve. I completely agree that one should choose the best tools. We just wanted to point it out because next time we may have a similar problem with easier problems. These days you try a lot to make easier problems slow languages friendly (Thanks :) ). If one looks at recent div3's he can clearly see are a trend that constraints of easier problems are set in such a way that slow input-output languages don't get TLE.

I cannot do anything with it right now.

We know just wanted to point it out for future div3s.

I checked a bit of your submissions and see that some of them are tightly fits the time limit

Those are someone else's submission. He asked him why he got TLE on that and how to improve it. Pypy3's IO is slow same soln written in Pypy2 will run fast. His in contest soln takes Time Limit/2 except for this F.

On a side note, he knows Python is slow but he also knows a lot of cancers in python.

Lol. At least it got an AC.
80141105 was the only soln is python which got accepted in the contest.
Only one soln in python is accepted so far 80171692 credits pajenegod.

TL;DR; vovuh Just don't enforce long ints in div3 just for the sake of it.

+1. Solved rest but couldnt do this.