Hello.
Sometimes I see wrong solutions in the top, because in tests some situations are not examined (
For example, “({)}” in “Brackets, extreme edition” puzzle (there is related topic for this case)
Unfortunately, at the moment there is no possibility to propose additional tests directly in web-interface to decline already accepted but wrong solutions.
The wrong solutions were posted before the new test-cases.
Codeforces has a “hacking” feature:
Find a testcase where the proposed solution is incorrect. If you are right and the program fails that testcase, you will be awarded points and the other solution is considered invalid. The testcase will be added to test other solutions with it.
I would like such a feature (ideally it wouldn’t be necessary, but some problems have insufficient validators), but I see that it requires some work to get it.