I’ve been stuck in Silver for a while. I’m a good programmer up to a point, if the solution is straightforward, but if there’s a twist, I often don’t know how to get it. For example, in Guess the Animal, I was completely stumped. I read the solution and saw that there was a little bit of proof technique. That makes me wonder if learning discrete mathematics could be helpful for USACO in general. There’s a Coursera course called Discrete Mathematics for Computer Scientists.