[dthunt]

Hey Aaron.

Communication via entity position is genius. Awesome! I wish my team had thought of that.

I have to say that being a contestant in 6.370 (robocraft/battlecode/etc) was easily the most fun, and the best practical experience I had while attending MIT. So, hats off to you and your partners for turning it from fun into excellent.

What I especially enjoyed about the 6.370 experience was the instructions constraint. With it being as low as it was, you really had to get smart about stuff like pathfinding - you could write a respectable AI using more normal approaches, but I suspect most contestants throw away traditional algorithms pretty quickly.

Less loved was that Java's compiler appears to hate (or maybe hated, at the time) efficiency. My teams usually wound up disassembling in order to find places where java was being stupid at compile time, and finding ways to get it to be less so. It makes a pretty big difference when every instruction counts. But, if it hadn't been for that, I might not have taken Compilers subsequently, so...

In any case. Thank you for your contribution to an enduring and truly excellent tradition in the MIT lexicon.

[Cixelyn]

Yeah navigation via A* / other traditional algorithms is almost always a no-go in Battlecode because of the way the bytecode limitation works. You almost always have to create some extremely custom pathfinding algorithm tuned to the constraints of the engine.

The simple algorithms are stuff like bugnav (walk in your desired direction until you see a wall then attempt to trace around it), but you'll find that even in something as simple as bugnav, there are a _ton_ of edgecases you have to account for in a discrete implementation that results in robots tracing around each other / stuck in infinite loops, etc.

Our 2012 bot uses a special implementation of the discrete tangentbug algorithm that allows us to precompute squares during rounds which we have extra bytecodes to spare[1]

It's probably _the_ most complex part of our codebase, and the person who wrote it doesn't even really understand how it works anymore.

[1] https://bitbucket.org/Cixelyn/bcode2012-bot/src/default/team...

[dthunt]

I think the last time we played, one of my teammates came up with 'detractors'; i.e. 'stay away from here, it's bad news', once a bot was sure that a place was not good for pathing, they would drop one and it would make its way around to the other bots.

That actually worked surprisingly well. Our implementation had briefly stupid behavior in a few scenarios, but after a lot of testing it was clearly our winner.

It looks like this year isn't as big on the pathing, as 'every square on the map is traversable, and there is no longer any distinction between ground and air units.'

That's mighty unfortunate. I thought that was one of the more interesting challenges.