My understanding is that the way they do this is have some number of model instances generating solution proposals, and then another model which chooses which candidates to submit.

I haven't been able to find information on how many proposals were generated before a solution was chosen to submit. I'm curious to know whether this is "you can get ICPC gold medal performance with a handful of GPT-5 instances" or "you will drown yourself in API credit debt if you try this".

Still extremely impressive either way.