What is pretest?
Is pretest just comes with thought: "We just want full-test contest, but we are running out of server. So, we will judge a subset of testdata, which we think quite strong with various edge cases." ?
Why pretests are not shown to us (including who locked their code)? Pretests are kind of hidden informations which can influence contest directly using hacking.
Actually what is hacking for problem coordinators?
My understanding is that even with unlimited server resources, there's still a reason to have pretests, hacking, and systests.
The way I think about it is that we wish to have strong tests, but sometimes problemsetters/testers miss edge cases and have weak tests. In that case, pretests => hacking => systests ensure we end up with stronger tests by the end of the contest. And we give points for hacking in order to incentivize users to spend time on hacking to strengthen systests.
(There's also another angle where hacking is fun for some people, but I think generally CF tries to have strong pretests, which isn't conducive to hacks.)
Are hack test cases automatically added to systests?
Yes, all SUCCESSFUL hacks are added to system tests.
What usually happens instead is that someone finds that the problem allows overflow or other super common problems to occur, and thinks of a trivial case to exploit that, and uses the same exact case for the codes that seem to be missing that detail, ending in ~+9/-2 hacks.
Pretests should be as strong as possible.
There should be also some contests without pretests, like topcoder
Are pretests weak? In which contests pretests are there?
What is wookje?
woookje with three o's
According to the oxford english dictionary, a pretest is something that goes before test.
Note that if you drink a cup of tea before system test, it is also considered as pretest.
I like codeforces!!!!