I don't know which criteria is used to select the problems difficulty. In round 78 DIV 1, almost the last 4 problems were solved by the same number of coders which is about 20 coders, and the first problem was solved by about 200 coders. These numbers don't make sense at all. Also this is not the only contest with this situation, it happened in many contests which was much harder than expected.
Another thing which I pointed before, and it's still exist, the problem stories are pretty long, why should I read more than 50% of the problem statement then I find it's completely useless?!
Codeforces admins, please give more attention to the problems in the contests.