Radit27GT's blog

How does Codeforces rating system work?
By Radit27GT, history, 3 months ago, In English

I do really confused by the rating system. Sometime I didn't submit anything like 0 problem solved but I get point, and then sometimes I did solved 2 problem on div.2, while I was low rating (div 4 maybe with 827 rating points) and I get minus point, this is really confusing really.

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3 months ago, # |
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https://codeforces.com/blog/entry/102
https://codeforces.com/blog/entry/50411
https://codeforces.com/blog/entry/117105

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3 months ago, # |
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When you register a new account your real rating is $$$1400$$$, but it is cosmetically shown as $$$0$$$. For the first $$$6$$$ contests on the platform you have a "placement period" when every contest really recalculates your rating but also adds a huge +delta by moving your shown rating closer to real rating. After first $$$6$$$ contests your shown rating is equal to your real one and "placements" are done.

This why you had $$$+36$$$ rating for 935 (Div. 3) and $$$-50$$$ rating for Global Round 25 both with $$$0$$$ tasks. The first one was your $$$4/6$$$ contest in "placements" with extra rating delta $$$+150$$$, in real rating it was $$$-114+150 = +36$$$. The second one was the last contest in the "placements", the extra rating delta was only $$$+50$$$, so, in total it was $$$-100+50 = -50$$$.

Your real rating is always recalculated based on your real position in the contest standings and your expected position in standings based on elo rating ideas with some adjustments. But in short: you will always gain more by performing better and you will always gain less by having a higher rating already. You can read about details in MikeMirzayanov's blogs.

https://codeforces.com/blog/entry/20762

https://codeforces.com/blog/entry/77890

Do not be afraid of losing rating at the beginning of your path. You will quickly gain it back with if you will participate more.

UPD: Actually new user rating is $$$1400$$$ now and placement takes $$$6$$$ rounds, I've added the link where these changes are described.

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    3 months ago, # ^ |
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    In addition, it is important not only how many problems you solve, but also the speed of solving problems.

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      3 months ago, # ^ |
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      Yes, more precisely only your position (Column #) in the standings matters. Everything else is just affecting your position in the standings.

      In ICPC contest rules it is based on the number of solved tasks and penalty time. In CF Round contest rules it is based on the number of points, which does not only include points from accepted problems but also points from hacks.

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    3 months ago, # ^ |
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    ah, thank you for your explanation, I just really confused about this, you know I'm new to this platform, and everyone just downvote my blog, I think I know how this platform works...

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