If the user solved problem P, he/she earns X / (Y + min(LIMIT, the_number_of_users_who_have_solved P)) points. The rating is a sum of the points he/she obtained.
Please note that, the formula as well as the parameters will vary with circumstances (e.g. the total number of users, problems and submissions) without notice. Currently, X = 100 and Y = 1, LIMIT = 400. (Last Updated: 2016/11/24)
Please also note that, now, the rating is not updated automatically.
The score for each category is derived from statistics of 'Category' tags assigned to each problem. The maximum value of each category is 100. The score is calculated in such a way that you can obtain high scores if you solve difficult problems (here, the difficulty is derived from the number of users who solved the corresponding problem).
The 'Category' tags are assigned by AOJ users. Thank you very much for your contributions.