In/Out Puzzles are created via a simple form on the CodinGame site. It's the most classic type of puzzle on CodinGame

Classic In/Out Puzzles

A player must return a response in the Standard Output stream computed from information read in the Standard Input stream. To validate the puzzle, the player must pass all test cases.

An In/Out puzzle contains a statement, a stub, and test cases.

You can find find more details about these in the Technical Details section:

To submit a puzzle for moderation, you must code a solution for your puzzle (in the language of your choice).

Tags and Difficulty

For a better description of the puzzle, you must also add tags and assess its difficulty.

Tags examples: Conditions, Graphs, Loops...

NB: Assess the difficulty based on the difficulty of existing puzzles, not on your ability to solve the puzzle.

Clash of Code

Clash of Code puzzles are simple In/Out puzzles specially created for short multiplayer battles. They're aimed to be solved in less than 15 minutes.

A Clash of Code puzzle must have at least 1 puzzle mode:

  • Fastest: the most classic mode; the first player who passes all test cases wins.
  • Shortest: also known as "code golf"; the first player who passes all test cases with the least number of character wins.
  • Reverse: same as fastest but the players should guess what to do (the statement is hidden, only tests are shown); the first player who guesses what to do and passes all test cases wins. No need to write a statement for a reverse-only CoC then

There are no tags nor difficulty associated with a Clash of Code puzzle.

Create your playground on
This playground was created on, our hands-on, knowledge-sharing platform for developers.
Go to
codingame x discord
Join the CodinGame community on Discord to chat about puzzle contributions, challenges, streams, blog articles - all that good stuff!
Online Participants