I have been noticing this for quite some time now, but I always just glossed over. Just wanted to share, so I'll make a short post about it.

I have seen quite a few problems that seem to have a very high difficulty(sometimes same as Div2C / Div2D) even though they are Div2A. For example: https://codeforces.net/problemset/problem/518/A

This is a pretty easy problem and I just can't fathom why it would be the same difficulty (1600) as for example: https://codeforces.net/problemset/problem/570/C or even a Div2D!!: https://codeforces.net/problemset/problem/735/D

I have seen this happen more often for older contests, but I may be mistaken. I figured, maybe I could find a reasoning if I read more about how problem difficulties are calculated: https://codeforces.net/blog/entry/62865 but from this it seems like that you have to be an expert to have a >= 50% chance at solving the mentioned Div2A problem. What??

It doesn't really bother me all that much, I just wanted to share and am wondering if anyone stumbled upon such "high difficulty" problems and if you have any idea why their difficulty is so high.

Hey guys, I'm cant seem to find a mistake in my code in problem 559B Equivalent Strings, I'm using recursive functions and expected TLE but am getting WA for test case 25. Can tell me what I did wrong? Sorry for my bad English, Thanks in advance :D https://codeforces.net/contest/559/submission/46421640