I was trying this problem. This problem is rated for 1600 but it seem easier to me than the normal 1600 question and this hold true for all the old question that i generally do. Does anyone have any idea how are problems rated and does they change over time to reflect the current rating.
does old question rating < new question rating. For same rating holds true?
You can check clist.by, as it estimates the rating of problems by the people who solved them, while codeforces just sets their own
Codeforces also estimates the ratings by people who solved the problem.
Then maybe old problems are high rated because most contestants couldn't solve them? In robocontest, for instance, simple mate in 1 problem(involving only a queen and kings) was rated around GM level.