Hmm.... again not difficult, but with a snag. I created a Map<String, File>, in order to be able to look up a file or directory given the name. That worked perfectly in the given test, but failed for the real thing. I thought all names were unique... be warned.
Just read the exercise. Indeed the problem is the inputfile. Three strategies come to mind: using a regex to determine the position of each letter, the positions of the letters are fixed, so require just some counting, and typing the piles into your code, which is probably the quickest way. Won't have time until this afternoon, though.
One remark though: in your Carey-test you create a list ar, that gets sorted. That means that from try 2, the argument-array is already sorted, and that saves a lot of time. I adjusted the test in two ways: one where each list is created in the method itself, and two where I create a general list, and in your method I take a copy and sort that. That gives quite a difference.
But the way to the outcome is much more interesting than the corresponding performance. and OP has quite a few solutions now. Hope he likes it.
Indeed easy again. But we haven't seen the last of it yet.... that hint to "longer numbers ...456...." probably means misery awaiting.
I used a record called Range, and I wanted to give it a constructor with a String parameter of the form "3-6". but I could not get that to work, some error about something being not canonical or likewise. So I added a static method Range of(String s), and that worked.