Having an unreachable return statement is a general problem; if used with recursion it just means you will not only get erroneous None return values, but also the occasional Stack Overflow. In your code: what happens when the recursion stack unwinds back to the original calling function and exits the if statement. What follows it? Nothing. Ergo None.

I don't know what inputs you're using locally. It's up to you to follow what path your code takes step by step for any given input. We can't do your debugging for you :)

Please don't post solutions/code in the discourse without the spoiler flag.

You have a return statement nested inside an if/else clause. This is a code smell. What if the if clause is always true, when does your code ever return ans? In Python, a function that doesn't have an explicit return value (or, in your case, an unreachable return statement) returns None by default.

I can't tell the solution here. But think if you can first reduce the range. That would be the first optimization. And then see if you're seeing some mathematical pattern.

Yes and by a lot

Yes.

Read Darren1182003's post below.

Are you getting an error, or are you returning something different than the expected? Please be more specific, since I'm on my phone I can't easily check for myself. Thanks!

However, while I agree both answers are symmetrical as per the question, they are not the same. So, you have to fix your code to match the answers on site.

I apologize, I meant to infer that the string had some inversion not reversion, meaning they are not the reverse of eeach other... rather some chars were switched

notice the error message:

"WX''0v0''XW" should equal "XW''0v0''WX"

so as far I as can tell, your code returns the reverse. do the expected answers on repl match the expected answers on codewars?

Hi, if you post code, especially where indentation matters, please check out using this markdown format to maintain the code.