Hi everyone!

After a contest Codeforces Round 1028 (Div. 2), i came up with an issue.

A solution that passed system testing during the contest was resubmitted after the round with no changes at all, and guess what it got WA23 322350733!

This made me wonder:

• were the testcases added after the contest?
• if so, shouldn't all accepted submissions be retested to keep things fair?

It's a bit confusing to see two different verdicts for the same code. If this kind of thing is possible, maybe it would be good to clarify how it's handled officially.

Has anyone seen this happen before?