It seems like in test 7 n=300, m=300, k=0. Answer is obviously 709227659, but it gives WA.

I also got answer 709227659 to this testcase.
Yes, seems like incorrect tests or incorrect problem statement.

Admins, please look at this issue. At least please check test 7.
Also please, clarify order of N and M values in input data (if they go in M,N order then correct statement please).

P.S.
  Also the problem is not so difficult as described in post-contest jury solutions. If problem statement is correct, it has got simple O(N*M) dp solution (based on https://en.wikipedia.org/wiki/Lindstr%C3%B6m%E2%80%93Gessel%E2%80%93Viennot_lemma principle).

Yeah, jury solution is complicated. Mine solution is a bit different, but still straightforward O(N*M*(N+M)) dp, with simple O(1) transitions from each state

Admins, any decision about this problem?
Is test 7 correct?

We fixed wrong tests. Original author miswrote 10^9+7 as 10000007 in his code, that generated incorrect tests. We sincerely apologize for such an error

Edited by author 28.01.2025 02:06

Thanks a lot for solving the issue!

Also, what about the original contest results ? ( https://timus.online/monitor.aspx?id=1568 )

Anybody now with correct tests has AC for problem M ? (suppose that such tests were on this contest too).

Edited by author 28.01.2025 19:43