If your representation means that a and b are encoded as the same thing, that means you need to change your representation!

It seems that you're representing trees as nested parentheses, where something like (()()) might represent a tree with two subtrees, each represented by (). But that's not necessarily a good representation: don't tie yourself to the notion that the string of parentheses has to look anything like the tree it represents.

I'm not sure how much I can say as a hint without giving away an answer, but maybe this might help. The four simplest strings of parens I can think of are the following:

""
"()"
"()()"
"(())"

Whatever mapping you choose, these will have to map to unique and distinct trees. Why not pick the four simplest possible trees, and see if you can spot a pattern?

I have the same problem.
With the condition that "" is a valid tree, I decide to make it a minimal tree (so that this definition would work recursively.)
This has a problem, because that means the tree

a = Leaf :*: (Leaf :*: Leaf)
b = (Leaf :*: Leaf) :*: Leaf

are both represented by:

a' = (()) -- a tree with one subtree
b' = (())
a' == b' = True

If I choose "" to represent Leaf, information are lost: I can no longer tell whether a subtree is on the left or on the right if there's only one subtree.

What could be a better way to model trees?
Thank you.

Fixed

Got the same problem in Haskell with a different case.

Falsifiable (after 18 tests):
  (17,457,139242075232141312)
expected: (97932708193302048,3,5)
 but got: (97932708193302041,3,5)

Ok. There are 20 users that solved the kata in Haskell.
I've seen another issue that akar-O raised for the Haskell version. Let me check if we can solve it.

Hi @casual dingbat. Which language?

yeah i didn't understand what bang meant

There's no reason that "()" has to represent a Leaf. You can decide on your own mapping when answering the question, as long as it forms a bijection any mapping is valid. I think most representations would have "" represent a Leaf, and "()" might represent something like Leaf :*: Leaf.

Oh ok... Well that's an issue... Can you post your code with a spoiler flag? I couldn´t get similar messages with mine.

I don't know if it's a real problem with the tests. Apparently they fail because ghc expects your function to return an Integer but it returns an Int. Try to fix that.

Hi. Please say which language and provide an example of test log. See here how to format your post: https://docs.codewars.com/references/markdown/#code-block