How it works?

Approved. Thanks :-)

bug fixed

Hi @rao4. Thanks for your translation.

Unfortunately, I cannot approve it yet because there is a bug in the random test cases. humanYears is supposed to be >=1 but this translation is passing 0 sometimes. Fix that and I will approve it. Thanks, DM

My issue isn't resolved, random tests still missing, but there's a "new issue" for this point... Don't resolve issues if they are still present! Your answer here is not an answer to my "issue", but your "main challenge ...realizing the array of strings..." (the string array is visible, so which kind of challenge do you mean?) and guessing what to do with these strings (which wasn't difficult too) is a gap in your description (Voile's issue);-)...

No matter what, finding duplicate characters is still a duplicate to many katas.

Just making the argument an array of strings does not make it not one.

Needs random tests

"what", "is", "yup", "zebra", "that"
Expected: 'a'
But was:  'h'

What is the definition of first duplication?

I have added non ASCII character to the test cases. Thank you for your feedback.

Some solutions assume there's only ASCII characters for 0 to 255. Either it should be specified in the description or there should be tests with other characters too.

The test case is checking for an uppercase as the first character eventhough the discription states case insensitive. As this was noted three months ago and has yet to be fixed this is another reminder.

Pretty sure this is a close (or exact) duplicate of at least one approved Kata - joining strings in an array has been done to death on CW. Please come up with something more original.

C#
Input ")"
Expecting true
But this is not valid