It doesn't matter if the above solution is copy/paste, it is ridiculously big. The actual solution is very small and simple using traditional addition method.

The messages that you've recieved on your failed test cases tell you what you've done wrong, also I believe you're trying to traverse a bad tree looking at the test cases. :)

Thanks for responding @taehwanjo. To follow up on some of your points:

You are erroneously equating the solvability of a kata with it deserving to be on codewars

Not my point. My point was that the kata is clearly solvable, so filing a bug that simply states that you were unable to pass a specific test case, without giving any additional details or eventually solving it and realizing a flaw in its wording, is not a substantiated bug report. It may just be that you got frustrated and filed a bug.

either the test is wrong or I don't know what recursion is

I'm sure you know what recursion is. However the kata has been around for almost 3 years and of all the issues mentioned in the kata, no one seems to be hung up on recursion. The kata does appear to have an issue with a test case involving removing a node, as opposed to inserting it - based off of the other comments. I haven't personally tried to solve the kata so I'm not sure about its details. This may be related to your issue. If so, its not clear that they are linked (and the issue is a duplicate), if not, then it would seem others did not stumble on that part as much, so more details would be useful.

My overall point was that while the kata may not be perfect, it has received enough completions and up votes from the community that it seems to be liked by others. Even the issues logged seem to be more of improvements as opposed to a fatal flaws that make the challenge impossible to complete. In general, I do agree with you that there should be a better system in place to encourage community contributions to existing kata. Perhaps some sort of bounty page where people can earn honor working on issues that kata have. However taking the kata completely out of rotation just because an issue is logged, IMHO, is too much of an assumption to make. Hopefully for now, seeing that issues exist on kata will help users make a decision about wether they want to spend the time on a kata or not.

I'm resolving this as an issue since the kata has been solved 287 times and the issue reported seems to be that the kata is not passable. If you can verify a specific issue thats not already logged than please file another issue with more details.

You make some fair points about lack of incentives to fix kata that are not in beta. However the example you gave is actually a perfect example of why we should not close the kata until the issue is resolved. You logged an issue that essentially states "I personally cannot solve this kata therefore there must be a bug with the kata". However the kata has been successfully solved by 287 people. It is clearly solvable.

There is nothing stopping people from logging issues and there is no way for us to automatically determine which issues really are issues. As another example, some people log issues for kata because they do not have example test cases - which is A: only a best practice, not required and B: wasn't even a feature until later on in the site (after maybe 600 or so kata had already been created). Its probably fair to call it an issue (I would go with suggestion, but ok sure we can call it an issue) - but not enough of an issue that the kata should be closed automatically. Some people log issues over very minor typos in the description. Yes they are issues, no they are not bad enough that the kata should be taken out of rotation.

With that said, I have recently deployed an update that will indicate the number of issues that are still active on a kata, that is visible from both the kata list and when training on the kata. This will at least warn users that there may be some issues. In terms of them being fixed, kata authors are notified about changes and many members in the community have the ability to contribute. Only at a certain point a kata becomes locked from major changes (500+ solutions). The description can always be modified. You are correct that there is room for improvements here, but I don't believe the fix is as simple as what you stated.

if you post your solution below and mark it as a spoiler maybe someone can help you :)

Also, you do get honor for logging an issue. You get 1 point for leaving the issue and 1 point for each up vote. Logging issues penalizes the kata from getting out of beta, but I don't see why we would penalize users. There is no developer on earth that doesn't right buggy code from time to time.

Thats not how it works. All kata must get through the beta process, which at the moment most people actually complain that it takes way too long to get out of it. Kata approvals have been opened up to more moderators over the past 6 months, so there may be lower quality approvals happening due to that - however even admins are unable to approve a kata unless it has no issues and at least 10 up votes and 5 completions have happened.

The most likely cause to quality issues is that kata translations do not go through their own beta process. They must be approved and their tests must pass, but if the kata is already out of beta then an approved translation will not be a part of the kata's beta process. This is the most notable area where improvements could be made - however having a beta process for translations is a large undertaking.

Kata on Codewars go through an entire beta process, where there is no ability to up vote at all but to indicate if you think the kata is ready or has issues. If you indicate it has an issue, its basically a down vote, until the kata author resolves the issue.

Even after a kata is approved, you can still file issues on a kata. Whenever you make a comment within the kata's discourse section you can indicate it as a suggestion or issue.

Codewars does this because down votes alone are not helpful. Without context as to why something is being down voted there is no useful feedback that a kata author could respond to.

I think this addresses one of my issues in that when I fail a test, often built around an edge case for the function, there isn't any output as to WHY it failed. Did I not address the issue in my solution or did the test just expect a different result for that case? I'll never know because I have no idea why the test failed until I finally give up and check others solutions, thus losing the ranking. Very frustrating.