Unhackable List

Правка en3, от eidan, 2019-02-14 23:10:00

Last round involved a randomized solution for problem E, and some pretests were aimed against std's rand() function. This caused a big dispute among contestants. It was questioned whether doing this type of tests was fair or necessary, since passing them depends merely on specific language knowledge, not actual problem-solving skills. Contest coordinators counter-argued that participants would've gotten hacked if it hadn't been for these pretests. They also stated that it's one's responsibility to know their favorite language when using it on a round. Since both sides had valid points.

The fact is, this controversy was really caused because of a technical property within C++ (and codeforces, partly), which many people had no clue existed. This is just an example of the fact that languages and their functioning in CF will sometimes have non-intuitive and unexpected properties, which may screw our performance in a contest. In other words, we are constantly exposed to bumping into another of these hidden behaviors, making the mentioned round hardly the last time something like this happens.

That's why I thought: We should have a list of the main language-specific issues that could annoy us during contests. Just a brief enumeration of not-so-fun facts about languages, such that, if not known, could break our solutions or get us hacked. Making a brief list available for the community, and exposing it to participants before a round could prevent a lot of trouble. If a problem could make you bump into one of these weird language issues, contest coordinators could safely assume we know about them and not get into an ethical debate whether it's fair to include tests against it. Also, contestants would be safe from losing rating to specific language knowledge. In other words, we could prevent issues like the last round's with the least amount of effort.

C++

Don't use rand()
Careful with unordered_map

Java

Arrays.sort() may cause TLE

История

 
 
 
 
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  Rev. Язык Кто Когда Δ Комментарий
en10 Английский eidan 2021-01-27 23:44:08 702
en9 Английский eidan 2019-02-16 20:32:20 8
en8 Английский eidan 2019-02-16 06:13:32 581 Tiny change: 'n instead.[More info' -> 'n instead. [More info'
en7 Английский eidan 2019-02-15 10:36:54 298
en6 Английский eidan 2019-02-15 10:20:34 176 Tiny change: 'n has low recursion limit">\n' -> 'n has low limit">\n'
en5 Английский eidan 2019-02-15 06:30:43 228
en4 Английский eidan 2019-02-15 00:22:49 878 Tiny change: ' a round. Since both side' -> ' a round. I think both side' (published)
en3 Английский eidan 2019-02-14 23:10:00 2284 Tiny change: 'se <math>O<sup>2</sup></math>. [' -> 'se <math>O(n<sup>2</sup>)</math>. ['
en2 Английский eidan 2019-02-14 20:28:05 1251
en1 Английский eidan 2019-02-14 19:28:54 971 Initial revision (saved to drafts)