I absolutely tanked the last div1 + div2, dropping to candidate master. But the ratings are temporarily rolled back, so does this mean my participation in this current contest (div 2) is unrated even after ratings come back?

I was looking at the Josephus Problem II in the CSES problem set, and couldn't find a c++ solution that didn't use ordered_set, which is not in the standard library. This made me wonder if I need to learn about other libraries to get good at cp. Any input appreciated.

Also if someone knows how to solve the Josephus Problem II only using the standard library please outline it for me ty

I'm reading through Competitive Programming 3, and the book recommends that you learn java on top of c++ to use biginteger. I don't know any java, so I don't know if it is worth it to learn just to use biginteger. I've never encountered a problem outside of the uva problem set that would be greatly simplified with biginteger, so I was wondering if any more experienced programmers could give some input. Thanks!

include <bits/stdc++.h> doesnt work for me. Is this supposed to happen? In tutorials, its usually there. Whenever i submit a solution with it, theres a compile error, and after I delete it and include the files individually, it starts working again. help?