Sunday, June 14, 2009

A lot more screencasts

I've been not updating the blog with the more recent TopCoder screencasts. I can't remember any spectacular parts of those except the last one since the matches were long ago, but here they go anyway:

TopCoder Open 2009 Round 4 (Streaming, AVI, MOV, AVI from Resubmissions on all 3 problems (if I remember correctly), was just lucky that nobody else got all three.

TopCoder Open 2009 Round 5 (Streaming, AVI, MOV, AVI from Tried my best and made almost no mistakes, but ACRush spent so little time on the hard. No challenges either, so the screencast is probably no so spectacular.

SRM 437 (Streaming, AVI, MOV, AVI from Couldn't figure out all the cases in the hard problem, although the approach I've chosen should be doable. Also underperformed during the challenge phase - but to be fairself-assuring, I didn't even have as many wrong 250 solutions in my room as ACRush has challenged, so there was little or no chance to fight for the win.

SRM 440 (Streaming, AVI, MOV, AVI from Wrote a reasonably logical solution for the hard - but rem has invented a brilliant way to express it in very simple terms, and thus his score is almost twice mine. Just one challenge with seemingly good prepared-before case - too little boundary in binary search - and then a couple of unsuccessful challenges on possible precision problems.

SRM 441 (Streaming, AVI, MOV, AVI from Once again my score on the hard is significantly lower than the best one due to me implementing an easy-to-invent but difficult-to-write solution - but luckily, ACRush resubmitted the medium. Several good challenges on a prepared-before case (forgetting about isolated vertices) - one more confirmation that such cases can be crucial when they exist.

SRM 442 (Streaming, AVI, MOV, AVI from Implementing the "TCO reslution": try the unusual strategies many times to see how they perform in the long run. Easy-Hard-Medium this time, turned out to be not so important since it was rather easy to solve all three (although rather hard not to make a bug in the medium). The screencast has an unusual feature at 48:11 - I had to stop the recording and restart it. Can anybody guess why (the screencast is no spoiler for this puzzle, so you can look at its nearby parts when figuring out the answer)?


  1. I tried a few times to download SRM440 (avi) and it "times out while connecting".

  2. 2rgrig:

    we're currently doing renovation in the room where my server is, so we have to switch it off frequently :)

    It should become more stable in a week or two.

  3. Could you please reveal the reason why you restarted recording :)

  4. Thanks for the wonderful screencasts!

  5. i can't access "streaming" can u adjust it as u do in 2010 streaming