Yesterday I got a message that my submission (180621980) for problem 1748C - Zero-Sum Prefixes coincides with mod_07's submission (180638882). I admit they are kind of similar but it was just a simple problem and I think that much similarity is normal.

Weirdly my solutions aren't skipped after rejudging, (in fact I got another +187! Wow! message) but his solutions are. I can assure you I did not cheat and I did not supply him my codes. Mentioning MikeMirzayanov.

I was trying to hack (my own solution) of DSU step 3 problem A and it got Unexpected verdict.

My Generator (spoilers are broken, so I am using pastebin)

I first searched it on google and found this blog, which says unexpected verdict means problems with authors solution. I hope this will get fixed (mentioning Aksenov239 for that).

Confusion about the constraint:

constraints for $$$n$$$ and $$$m$$$ is $$$\leq 2 \cdot 10^5$$$ in this problem. If I take $$$n = 10^5$$$, $$$m = 2\cdot10^5$$$ and in the first $$$\frac{n}{2}$$$ queries I connect the first $$$\frac{n}{2}$$$ sets and in the last $$$\frac{n}{2}$$$ I connect the last $$$\frac{n}{2}$$$ sets, then connecting $$$\frac{n}{2}$$$ and $$$\frac{n}{2}+1$$$ should take $$$\frac{n}{2}$$$ time. If I keep connecting $$$\frac{n}{2}$$$ and $$$\frac{n}{2} + 1$$$ and rollbacking for the rest of the queries then the time complexity should become $$$\frac{n^2}{4}$$$ and it should get TLE.

If there is a way to solve this please share that. (Cause I don't know how to do that >_< )

Someone (handle — eat_sleep_flirt_repeat) sent me solution (not sure correct or not) of problem B of round 665 in talks while contest was running. And I don't even know that person. Now I am not sure what I should do so I am writing this as a blog. Please help me.

EDIT : another thing, I didn't noticed that during the contest and I didn't use the solution.