A while ago, I posted this blog. I was wrong.

In CodeRush May '23 (a contest with prizes), problem E was copied from yukicoder. The sample input is also almost the same: the CodeRush organizers just made it weaker by removing the last 2 queries!

Problemsetters, please stop.

Wtf man. I was happy getting 3rd place in this. :'(

I mean every problem is stolen because every problem is on luogu.

Another (unrelated) fun fact: in some CodeRush contests there are prizes for the first solve of each problem. In this contest, the first solve to problem A was a copy-paste from ChatGPT.

Can anyone give any hints for problem D where we are given an array of size n and then m constraints about pair sum.

Construct the graph, now think for trees, you would find that setting any value x for a node satisfies the sum condition accordingly (lets forget the condition 1<=x<=k for now), Now if there is a cycle you would find similar thing for cycles of even length, but cycles of odd length has an unique x (for a node). So for each component check if it is bipartite or not, if it is not bipartite there can be at most 1 solution, otherwise you check the max and min value for all the white nodes and max and min for all the black nodes (initializing any of the node with 0) now set the (1 <= x <= k) condition for these corner points (max and min) and count the valid cases, this is done because if we increase the value of any black node by 1 then value of all the black nodes increases by 1 and all white nodes decreases by 1. So now you have a solution where the maxima is at most k, do the same for k = k-1 and subtract the result.

Where it's stated that there were prizes?

In the e-mail I received. Anyway, it turned out that "prizes worth $$$360$$$ dollars" means something like "$$$100$$$ Amazon coupons worth $$$3.60$$$ dollars".

Oh, I see. I also saw some mention about prizes somewhere for one of the CodeRush contests, but when I checked contest page and saw nothing — decided that it's a mistake (earlier they had detailed prize descriptions on the contest page).

This makes me feel that CP problemsetting is eventually becoming harder and not many unique problems can be framed any longer.

CodeRush May '23 problem D is same as yukicoder1502. CodeRush March '23 problem F is same as yukicoder941.

Let's rename CodeRush to Yukiclone.