Perhaps most importantly, I hope you will have a good idea about just what can be done with C, and what can’t, so that you will be able to further develop your skill at using C as the need arises. FINITE SUMS AND INTEGRATION § 11.1 How Much Water Can a Water Tower Hold?§ 11.2 Numerical Solution § 11.3 Analytic Solution § 11.4 Just How Much Water Does the Notrees Tank Hold, Anyway?
You all know what it feels like when something is too hard: the dreaded "I have no clue what's going on".
Anything not too close to either extreme is probably fine.
Problem solving is more of an art than a science, and it can only be learned through experience.
I hope these notes and the homework exercises will help you to develop this important ability early in your academic career. The first is to show you some of the ideas that you will encounter a little later in your academic career, and to solidify your grasp of some ideas you have seen already.
(Reason: the existence of $X$ is not a Nash equilibrium.) There are plenty of strategies which obviously work like "do nothing" and "read solutions without trying any problems", but beyond that anything reasonable is probably fine.
If you had to force me to say what I thought was the biggest predictor of success, I would say it is whether you think about math in the shower.
The purpose here is not to make you proficient at circuit analysis, but rather to introduce you to the basic ideas, such as just what is a current or a voltage.
Then, when you encounter the subject again in considerably more detail, you will have some understanding and familiarity to fall back on.
With that disclaimer, here are some possible suggestions for math olympiads.
Younger students (preparing for AMC/AIME) would likely benefit from books or classes from Art of Problem Solving, like Volume 2.