Codyssi - Leaderboard Criteria Explanation!

Do I need to know these criteria?

No, you don't need to know these metrics to participate and have fun in Codyssi!

This is simply an explanation for those who are curious about how points are calculated on Codyssi :>

What do the 'Judging Type' options do?

There are 3 different 'judging type' options that you can choose from. Click on each judging type below to find out more:

• Difficulty Based

  The difficulty-based judging type considers the difficulty rating of a problem part when allocating points.
  
  For each relevant problem part, points are calculated as follows:

  • The maximum number of unweighted points per problem part is determined by the formula M = minimum(100, N). For example:
  
  
  • If a leaderboard has 50 users, the maximum number of unweighted points per problem part will be M = 50.
  
  
  • If a leaderboard has 150 users, the maximum number of unweighted points per problem part will be M = 100.
  
  
  • Unweighted points are allocated by time taken to solve the problem part, measured from when the problem was released. The first user earns M unweighted points, the second earns M-1 unweighted points, the third user earns M-2 unweighted points, and so on. Finally, the Mth user earns 1 point. The other users earn 0 unweighted points for that part. For example:
  
  
  • If a leaderboard has 50 users, the first user earns 50 unweighted points, the third earns 48 unweighted points, the 50th earns 1 unweighted point, while the 51st earns 0 unweighted points.
  
  
  • If a leaderboard has 150 users, the first user earns 100 unweighted points, the third earns 98 unweighted points, the 50th earns 51 unweighted points, while the 101st earns 0 unweighted points.
  
  
  • Then, the points are weighted by multiplying by the difficulty rating. This means that more difficult problems are worth more for the difficulty-based judging type. For example:
  
  
  • If a user earns 50 unweighted points for a problem part with a difficulty rating of 5, they will earn 250 weighted points for that part.
  
  
  • If a user earns 25 unweighted points for a problem part with a difficulty rating of 3, they will earn 75 weighted points for that part.
  
  
  • The weighted points for each user are then added to their total.

  This process is repeated for each relevant problem part (adjusted by the settings below). Finally, the top users are displayed in order of their total weighted points.



• Problem Based

  The difficulty-based judging type does not consider the difficulty rating of a problem part when allocating points.
  
  For each relevant problem part, points are calculated as follows:

  • The maximum number of unweighted points per problem part is determined by the formula M = minimum(100, N). For example:
  
  
  • If a leaderboard has 50 users, the maximum number of unweighted points per problem part will be M = 50.
  
  
  • If a leaderboard has 150 users, the maximum number of unweighted points per problem part will be M = 100.
  
  
  • Unweighted points are allocated by time taken to solve the problem part, measured from when the problem was released. The first user earns M unweighted points, the second earns M-1 unweighted points, the third user earns M-2 unweighted points, and so on. Finally, the Mth user earns 1 point. The other users earn 0 unweighted points for that part. For example:
  
  
  • If a leaderboard has 50 users, the first user earns 50 unweighted points, the third earns 48 unweighted points, the 50th earns 1 unweighted point, while the 51st earns 0 unweighted points.
  
  
  • If a leaderboard has 150 users, the first user earns 100 unweighted points, the third earns 98 unweighted points, the 50th earns 51 unweighted points, while the 101st earns 0 unweighted points.
  
  
  • The unweighted points for each user are then added to their total.

  This process is repeated for each relevant problem part (adjusted by the settings below). Finally, the top users are displayed in order of their total (unweighted) points.



• Time Based

  The time-based judging type only considers the number of problem parts solved and the total time taken to solve those problem parts.
  
  For each relevant problem part, the process is as follows:

  • If a user has solved that problem part, 1 is added to their score.
  
  
  • For example, if a user has solved 3 relevant problem parts, then their score will be 3.
  
  
  • If a user has solved that problem part, then the time taken to solve that part is added to their total time.
  
  
  • For part 1, the solve time is measured starting from the time the problem was released.
  
  
  • For part 2 and part 3, the solve time is measured starting from when the user solved the previous problem part.
  
  
  • Examples of total score and total time calculations are provided:
  • User A solves part 1 of a problem in 3 minutes and then solves part 2 of a problem in 2 minutes. Their total score will be 2, and their total time will be 3 + 2 = 5 minutes.
  
  
  • User B solves part 1 of problem 1 in 2 minutes. They then solve part 1 of problem 2 in 5 minutes. Their total score will be 2, and their total time will be 2 + 5 = 7 minutes.
  
  

  Then, the top-scoring users are ranked by total score first. If there are ties, then the ties are broken by their total time. For example:

  • If user A has a score of 3, while user B has a score of 4, then user B will be ranked above user A.
  
  
  • If user C and user D both have scores of 3, but user C has a total time of 5 minutes, while user D has a total time of 7 minutes, then user C will be ranked above user D.
  
  

What do the other criteria options do?

The other criteria options are used to filter the problems or problem parts that you are interested in. Click on each criteria option below to find out more:

• 'Problem Set' options

  The problem set option is used to indicate which problem set to focus on.
  
  For example, you can view the top-scoring users for the problems in the Codyssi 2025 contest round.



• 'Individual Problem' option

  The individual problem option is used to focus the leaderboard on a single problem. The problems you can choose will be determined by the problem set option (above). For example, you can view the top users for only problem 1 of the Codyssi 2025 contest round.
  
  For example, if you want to change to view the top users for problem 2 of the Codyssi 2024 sample round, then you'll have to change the problem set option first, then change the individual problem option.



• 'Problem Part' option

  The problem part option is used to focus the leaderboard on specific problem parts.

  • The 'Part 1' option is used to view the top users for only part 1 of the problem(s).
  
  
  • The 'Part 1 and 2' option is used to view the top users for only parts 1 and 2 of the problem(s).
  
  
  • The 'All Parts' option is used to view the top users for all parts (1, 2, and 3) of the problem(s).
  
  

Why do my points change between leaderboards?

For the 'difficulty-based' and 'problem-based' judging types, the points you earn are relative to the performances of all other users on the leaderboard.

As different leaderboards may have different members, then your points may change between leaderboards if you are using these judging types.

As a side note, the 'time-based' judging type never changes between leaderboards.

Do I have to compete for a spot on the Codyssi global leaderboards?

No, you don't need to compete for a spot on the Codyssi global leaderboards if you don't want to. You can still participate, solve problems, and learn in Codyssi.

The global leaderboards are provided to acknowledge excellent performances and to create challenges for ambitious or competitive programmers :>