The Fumbling Bumbling ACM ECNA Regional

The test data for the regional was finally published. One test case for problem B violated the input spec. My team (CMU Tartans) solved that case "correctly" (whatever that means for an invalid input) while Waterloo Black and CMU Dragons solved it "incorrectly". Those runs will have to be rejudged and the scoreboard recalculated.

To preface this I will say that I am pissed because there is a good chance that after being a regional winner for 5 days there is a good chance we won't go to world finals. Right now it looks like Waterloo got 1st, CMU Dragons got 2nd, CMU Tartans got 3rd, and Michigan got 4th.

The first big mistake was not checking the test data. I helped create the problem set for the CMU Invitational. For all of the problems I wrote I made my solution check the input format and verify that all of the test cases were valid. It is a simple sanity check to make sure the problem specification matches the test cases.

The second big mistake was not checking the test data right after the contest. The problem decided world finals spots its probably worth checking. If they had asked either of the two top teams that missed the problem with many resubmits they would have been told that there is a decent chance of a bug in the test data. If they had looked at the one test case which everyone was failing they probably would have seen the bug. Instead they just glanced over things and missed it completely. They should also have realized that they screwed up test data the last two years, which means there is a decent probability they did it again.

It is hard to write a completely correct problem set, but it isn't that hard. More importantly the contestants deserve a better contest. We practice countless hours to do well in this one contest, and they can't put in the time to make sure that their problems are correct?

There was another, smaller, error in the problem set. On problem H the number of queries is not limited. Thus there is a valid input file of infinite size. When we first read it we thought that you might need some fancy data structure because their could be a huge number of queries. It turns out that nothing special is needed. The problem is that for every solution judged correct there is a huge input file that makes it time out. That didn't cost us the problem, but it definitely cost us time penalty.