I have solved one question in December long challenge successfully then also my rating has decreased. Similar case happen in November long challenge ! I am not able to figure out because of what my rating is decreasing?
here is how rating in codechef is calculated https://www.codechef.com/ratings
and your rating also depends on how others have done in the contest .then it is being compared . go and check that link. don’t get demotivated due to fall in your rating be motivated always and try to learn new things from every challenege .