JiaZeWei's blog

About the rating of problems on Atcoder and CF
By JiaZeWei, 3 years ago, In English

You can see the ratings of problems on Atcoder on https://kenkoooo.com/atcoder/#/table/

But what exactly is the connection between rating of problems on Atcoder and on CF.

I'm recently solving problems with dif between 2400 and 2600 on CF. What does it match on Atcoder?

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3 years ago, # |
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There's no match since the problems are essentially too different.

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    3 years ago, # ^ |
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    Your statement implies,that are there are 2 non intersecting sets of problems,CF and Atcoder,but I think there are several CF problems that have been inspired from atcoder, or related to atcoder problems.

    And it is difficult to quantify the similiarty of CF problems,since they are too different from each other.And I AFAIK CF doesn't impose any blueprint or template to problem setters, and any guideline imposed is so broad that it can house most of the atcoder problems.

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      3 years ago, # ^ |
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      Have you solved any Atcoder problems (I mean ARC and AGC; ABC is just classical problems)? The difference between styles is very pronounced and noticeable from the moment you start solving.

      Your statement implies,that are there are 2 non intersecting sets of problems

      They are not "non-intersecting" (and it didn't imply that), but the average CF problem and the average Atcoder problem differ significantly.

      And I AFAIK CF doesn't impose any blueprint or template to problem setters

      I don't know what you mean by "blueprint", but both Atcoder and Codeforces have coordinators that do not just accept any problems (cue stories about Anton rejecting 72 problems etc). The vision of the coordinators affects problem style a lot. Possibly most Atcoder problems could've been accepted by Codeforces, but definitely not vice versa.

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        3 years ago, # ^ |
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        What I meant is, CF problems themselves are extremely diverse, I have seen some really classical problems, and some really weird problems(not in a negative sense).

        If you randomly give me a problem, and ask me where it was taken from, most probably I wouldn't be able to say it's origin just from it's nature.

        There are some CF problems that are more similar to Atcoder problems, than to any other CF problem.

        https://codeforces.com/contest/1406/problem/B

        https://atcoder.jp/contests/abc173/tasks/abc173_e

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          3 years ago, # ^ |
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          I feel like there's a scale of these things, something like Codechef-Codeforces-Atcoder. Atcoder problems are heavily on the atcoder side, codechef sometimes blends in with more implementation heavy cf rounds and cf rounds depend completely on the author and coordinator but if you look at the contest as a whole (and not single problem from a contest in isolation) you'll know it's cf.

          Edit: as -is-this-fft- said, forget about ABC, OP is talking about 2400-2600 rating and we don't mention ABC when talking about real atcoder problems.

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      3 years ago, # ^ |
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      Yes, cf problems are often not atcoder-like. In fact, I don't like problem ratings because as you said problems are too different to compare, I've seen problems around 3000 rating that are easier than certain problems around 1800 rating to me (this "to me" is important) and this fact is even more important in atcoder where if you don't get some observation you might solve BCDE and not solve A. If you really want to force comparison, then if you're practicing on 2400-2600 cf rating problems you can try solving the first couple of problems in AGCs and solving ARCs (including old ARCs).

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