My advice is to study the input and outputs and try to work out why your code doesn’t work.
For testcase 4 I imagine you get something like:
Compare the expected result and the result from your code and consider which part of your code is causing that to happen.
Think about where .lower() casting is necessary and where it is not.
i think it is necessary evrywhere but how do i change it back at the end
is anyone here
I’ve given you the information required to solve the issues you’ve mentioned so far, I will send you a private message to explain further to avoid cluttering this thread 
+1
Me too.
Curiously it succeeded exactly once but not ever since.
I also tried using string_view in map keys but it fails to hash properly (string_view are notoriously not advised within maps).
Looking at some of the top answers, I feel like I over-engineered mine, using regex and limit checks. I saw it mention alpha-numeric and then alphanumeric with some punctuation, so I just assumed they should be validated.
