You may have noticed that we now show an edit summary on Community Wiki posts:

community wiki
220 revisions, 48 users

I'd like to also show the user who "most owns" the final content displayed on the page, as a percentage of the remaining text:

community wiki
220 revisions, 48 users
kronoz 87%

Yes, there could be top (n) "owners", but for now I want the top 1.

Assume you have this data structure, a list of user/text pairs ordered chronologically by the time of the post:

User Id     Post-Text
-------     ---------
12          The quick brown fox jumps over the lazy dog.
27          The quick brown fox jumps, sometimes.
30          I always see the speedy brown fox jumping over the lazy dog.

Which of these users most "owns" the final text?

I'm looking for a reasonable algorithm -- it can be an approximation, it doesn't have to be perfect -- to determine the owner. Ideally expressed as a percentage score.

Note that we need to factor in edits, deletions, and insertions, so the final result feels reasonable and right. You can use any stackoverflow post with a decent revision history (not just retagging, but frequent post body changes) as a test corpus. Here's a good one, with 15 revisions from 14 different authors. Who is the "owner"?

https://stackoverflow.com/revisions/327973/list

Click "view source" to get the raw text of each revision.

I should warn you that a pure algorithmic solution might end up being a form of the Longest Common Substring Problem. But as I mentioned, approximations and estimates are fine too if they work well.

Solutions in any language are welcome, bu

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