Hello codeforces
yesterday there was a div4
at the middle of the contest
I noticed that a large amount of coders came up with the solution of problem E at the same time
so (as I am unrated for div4 contest)
I did some search on internet
and found a live stream that is currently solving the problems
so I see the code of problem E
and I would say that it is very familiar to a lot of codes that get AC here at the time that it published
now a lot might say why would i care about div4
a lot of people waits div4 for positive delta
and I know coders that was getting around +100 rating
but because of that they got negative delta because they didn't come up with problem E
I will add some photos
my point is
cheating is bad for you
but if you don't care
just don't ruin contest for other people
Thanks Anas!!
This is really a serious issue
You are welcome.
Thank you very much; I couldn't solve problem E either. Still, I don't find much sense in 'hacking' the solution; you don't end up learning anything.
By hacking solutions one learns about how to come up with testcases which can break a solution and its a very important skill for both, problem creation and solving.
I think by hacking he meant cheating not actual hacking round
Exactly.
not defending the cheaters, but the problem is pretty standard and the solution is obviously very likely to coincide so you $$$might've$$$ gotten the wrong people ? idk.
Such a beautiful poem.
Each line has a very profound meaning
I wish I could
Write a beautiful poem like this
keep going you are getting better
It may get hacked later due to an unordered map ;)
Can someone please explain why does the std::unordered_map gets hacked, but the std::map doesn't? Isn't the unordered one faster than the normal?
unordered is linear at worst
"collisions"
Unordered map uses hashing to store and retrieve elements, and a common problem in hashing is 'collisions' which will lead to complexity of O(n) in worst case for each operation done on the map while the normal map uses binary trees (Not sure), so the complexity will remain log(n) whatever values it has.
Thank you
Welcome
Thanks Anas_Da, people like you keeping people like us motivated by exposing cheating. In recent times rejudgement of previous rounds are great for me.
Oh, unordered map without safe hash, is there any blog on how to hack such unordered maps?
https://codeforces.net/blog/entry/62393
No, not this, i wanna know how to hack not how to not get hacked
This might explain the inf unordered_map hacks in the last div 4
last christmas, i gave you my code
but the very next day, you just got skipped
this year, to save me from -ve
i'll give it to someone with cheating skills
I suggest not allowing people to comment on tha main blog of the contest during it, as they always hike people from there .
Thank you for trying to expose cheaters and I wish that Codeforces act soon so we can make this platform a better place for CP-ers
What do you suggest codeforces does?
I see that the solution uses an unordered map and according to my experience with unordered maps mostly there is a case that takes o(n) time rather than o(logn) so the solutions must've already been hacked by other coders. I don't think there is any reason to worry over the petty code codeforces will surely adjust the ratings after removing the cheaters.
They got the hacks they deserve.. I guess it was leaked on purpose to do more hacks. xD
https://codeforces.net/contest/1915/submission/239288878
I didnt watch the youtube video you are talking about and still have similar code to those you have refered to. The problem was just typical.