Contributions and tiers

Contribute to problem information

After logging in and solving a public problem (AC), you can contribute regardless of your tier. Open the “Contribute” tab on the problem page and select the difficulty you experienced and tags you used. You may submit either difficulty or tags alone, and select up to 10 tags.

Each person has one contribution per problem. If you still meet the eligibility requirements, you can edit or withdraw it on the same page. Aggregate results are recalculated after each change. Other contributors’ individual choices and identities are private.

How difficulty and solution tags are determined

Problem difficulty has five levels: Bronze, Silver, Gold, Platinum, and Diamond. With no votes, a problem is Unrated. The first vote already affects community difficulty and SP. Every vote has equal weight, regardless of age.

• With 1–9 difficulty votes, use the median. For an even number of votes, round the average of the two middle levels.
• With 10 or more difficulty votes, exclude a rounded 10% of votes from each end of the sorted list, then round the average of the remaining levels.
• Solution tags selected by at least 60% of contributors who chose a tag become primary tags; 25% to under 60% become alternative tags. Both appear in problem details and the list. Contributors who chose no tags are excluded from this percentage.
• Newly proposed tags start as candidates. A tag becomes official when three distinct users select it across one or more problems. It is removed when its last user deselects it.

Solve points (SP) and user tiers

Earn difficulty based SP for each distinct problem with a current AC result. Solving the same problem again does not grant more SP. Unrated problems count after their difficulty is set. Test runs alone do not earn SP.

Before earning your first tier, you are Unranked. Current SP is recalculated after difficulty changes or rejudging and may rise or fall. Your highest earned tier does not fall from ordinary difficulty reclassification.

Contribution history and rankings

Contributions do not earn SP, but your first opinion on each problem earns 1 credit, except on problems you authored. The contribution count is the number of problems you currently have an opinion on plus the published problems you authored. Difficulty and tags for one problem, or an opinion on your own problem, count as one. Editing does not increase the count; withdrawing an opinion or deleting an authored problem removes it.

Your profile shows current SP, highest tier, progress toward the next tier, and contribution count. Rankings use the selected metric of points, contributions, or longest streak; ties share a rank. The longest streak is the longest run of consecutive days with a submission in Korea time. Any submission counts regardless of its result, several submissions in one day count as one day, and test runs are not included.