Guess my mentor is the same one! I finally solved the problem using only functions in the String module. It works although very inefficient.
satoru
malaire
Does your solution handle Unicode lowercase letters which doesn’t have uppercase version, and so String.upcase will return the same lowercase letter?
From Character Properties, Case Mappings & Names FAQ:
Q: Does uppercasing of a string eliminate all of the lowercase letters in it?
A: No. Some letters (notably those in the IPA block) have no matching case equivalent. As a result, uppercasing a string may not eliminate all of the lowercase letters in it.
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satoru
I checked String.upcase(input) == input and String.downcase(input) != input. Slow but get all the tests passed.
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malaire
That doesn’t work for all Unicode characters. IMO the exercise is badly made if solution is intended to be Unicode-unsafe.
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