I think the test cases are weak, the extra notes at the bottom of the description are not tested at all. (I passed without considering self loops)

As always

Hi,

That's a duplicate (peek most of those). You shouldn't republish it. You still can fix it if you want, to get feedback about the kata creation process.

Cheers

Re-raising the comment below as issue:

The tree may be balanced or unbalanced, but it is always sorted

Then why are invalid trees being passed in in the actual tests?

Needs random tests.