I've been working on this all afternoon, and I'm reasonably close to done (though I might not get to finish until tomorrow). When I'm done, how should I submit my entry? Just post a github link here?
yea post it to GH i guess and put in your XCP/BTC address, then we just need someone like Adam to look at it and say the contract should operate and the donors will send the XCP your way.
it would be nice if we could actually test it on the bitcoin testnet but i have no idea if that is currently possible to do. ideally that would be the best proof that it works.
You might want to add a little disclaimer to the code for people to only use it in places that allow private lotteries (like in the UK although there are restrictions and limitations).