Have you been wondering what is the difficulty of Code Jam problems on a codeforces scale? me too.

I tried to make an estimate for the 2021 qualification round (link), and I plan to do it also for the upcoming rounds. I share here the process, the results, and I welcome any feedback to improve.

Data: - CJ contest result data, downloaded using vstrimaitis code, see details in his great blog post. From here I get the list of contest participants and what problems they solved. - CF users data, downloaded using CF API. From this, I get the current rating of every CF coder.

I assume that many coders use the same username across different platforms. If for a given CJ contestant I find a CF user with the same name (case insensitive), I assume they are the same person.