One thing I do when I'm stumped by "WA" evaluations is write a testcase generator (I did that for the chess problem in this round). Although in this particular case I have no good idea of how the generator would produce the expected answer, other than by running the same algorithm as the real solution which obviously defeats the purpose.

For me, these problems are about 10% getting the right answer, and 90% trying to get it fast enough.

Here, for instance, I calculate 11, which is presumably correct?

Perplexed by Problem A's memory limit hit. There's absolutely no way I allocate 1 GB of memory for an 1000 * 1000 problem.
If however there is a typo and the limit is actually 1 MB then I need to rethink my solution...

Every scenario I devise I test by hand to check the result, and the algorithm does it correctly. I've tried branching, multiple branching, nested branching, re-combining, isolated structures. Nothing doesn't work. Most probably I'm still missing some fundamental concept.



Here, for instance, I calculate 11, which is presumably correct?

I seem to be having an odd problem parsing the file in problem 5. My parsing routine works fine for the test file and case 1 (which is probably the same thing), but it's crashing on the second test case. It's almost as if there's a blank line somewhere in the input file, but there's nothing about that mentioned in the problem specification. Anyone else run into a problem like this, or do I just have some silly parsing error somewhere?

Edit:
Or perhaps the test cases are not terminated with a -1 as specified? That could cause the problem.

I can catch the exception and make it give a solution, but when I get a wrong answer I can't tell if there's something wrong with my parsing or my solution algorithm.

You mean problem 6 (XYZZY) right?

Every scenario I devise I test by hand to check the result, and the algorithm does it correctly. I've tried branching, multiple branching, nested branching, re-combining, isolated structures. Nothing doesn't work. Most probably I'm still missing some fundamental concept.



Here, for instance, I calculate 11, which is presumably correct?

Agree with bernds, edge cases are probably what's biting you. Try something sillier, like below (my output is 0, 2, and 41 respectively):

Cool, I get 0,1,34, so something to look at.

I seem to be having an odd problem parsing the file in problem F.

I had a similar problem until I noticed that the description says "The input for each room consists of one or more lines containing:".

Best regards,

Ulrich

Guess I'll be learning something when Solomon posts how to approach problem B. I have a solution (I think), it's just too slow. Maybe I'm missing something obvious, or maybe I somehow need to treat this as more of geometry problem. Hmm.

I have pretty good ideas on how to solve E (Build Dependencies) and F (XYZZY), and will try to solve them before Mother's Day (US edition) dinner, but D (Chess Tournament) I'm not so sure. Only way I can see it modeled is a mixed graph with directed and undirected edges, but that just sounds like a nightmare and I'm unversed on any algorithms for handling mixed graphs. Whatever I manage to get, I will write how I solved tomorrow before work.