Potentially Plagiarized Kata

This wiki is supposed to contain katas which are potentially plagiarized or copied from other sites without proper credit.

If you add a kata here, please add some information on it, including a site it comes from, and what action should be taken to rectify the problem (add credits, delete the kata, etc.) You can also add some general notes about the licensing information of the original site if it's not already here.

If copied kata is still in beta, a post labeled issue should be raised in its discourse to prevent its approval, and an issue should be raised in Codewars Github repo, so admins could retire it before it gets accepted.

Some topics are very popular, so it can be difficult to tell if some problem is a copy, or not. Sometimes you can find some hints, like exact wording, exactly the same examples, etc. In case of any doubts state them here, and use your common sense to judge the extent of the issue.

List of kata

HackerRank

• Minimum unfairness of a list/array | Max Min

SPOJ

• STRONGN Strong Number (Special Numbers Series #2)
  • Possibly a copy from SPOJ: https://www.spoj.com/problems/STRONGN/
  • "Strong numbers" seem to be somewhat popular topic of coding problems, but presence of STRONGN tag suggests it was heavily inspired (to say the least) by SPOJ platform.
  • I could not find any information on licensing of SPOJ problems.

Issues

Some lists were moved to Issues board to help with tracking:

• https://github.com/codewars/content-issues/issues/42
• https://github.com/codewars/content-issues/issues/43
• https://github.com/codewars/content-issues/issues/44
• https://github.com/codewars/content-issues/issues/46

Licensing information of exploited sites

Codeforces

Licensing information can be found here: https://codeforces.com/blog/entry/967 . Most important excerpt would be:

You may publish the texts of Codeforces problems in any open sources, but you must preserve a direct link to the site http://codeforces.ru (http://codeforces.com for English statements) and indicate Codeforces as the problem source. These data should be located in close proximity to the statement, be easily noticeable and readable. It is forbidden to publish Codeforces problems in open sources supporting automatic testing (such as online judges or similar resources).

This probably means that all problems "inspired" by Codeforces must be removed from Codewars.

Project Euler

Licensing information can be found here: https://projecteuler.net/copyright

Can I make use of the problems elsewhere?

Yes! It is not only granted but it is encouraged for material to be shared and used freely for non-profit making purposes. But please read on...

[...]

Do I need to show attribution?

Under the CC Licence it is a requirement, but it should also be a matter of courtesy. You are entirely at liberty to use the material as it is or adapt it. If you choose to use the content as it appears on the website, then you could say something like, "The following problem is taken from Project Euler." If you modify the problem then you could say something like, "The following problem was inspired by Problem xxx at Project Euler." But please note that the terms of the licence require that any derivative work will be subject to the same licence.

This probably means that each problem originating from Project Euler needs credits and preferrably a link to original problem.

Kata which have been already handled

• Jackie's Game (unpublished)
  • Copy of Godsend problem from Codeforces