It took me a long time to realize what this level was asking for, but I finally narrowed it down thanks to the guides. If you still don't understand after that, let me try to explain in a slightly different way: The level is asking "if one letter is different from adjacent letters, return true" but what it should say is "if there is only one instance of a single letter, return true." If there are more than one single character (i.e. baac, B and C) or if the string contains no single characters (i.e. bbc...

By elegant, I mean a solution that would work on a string of any size and thus the b=aaaaaa type of solutions wouldn't work. I've got it down to 9 lines, but I can't think of a way to to pare it down further. ba=ab cb=bc ca=ac b=xy yx=xy ax= yc= xc=(return)true =(return)false ...

I guess I don't understand what this problem wants. Personally, I think the problem statement is poorly worded. How can there ever be "exactly one letter that is different from adjacent letters"? If an "a" is adjacent to a "b" in a string then both the "a" and "b" are "different from adjacent letters". Namely, the "a" is different from the "b" it is adjancent to and the "b" is different from the "a" it is adjancent to. So there are 2 letters which are "different from adjacent letters". Does it mean exactly...

In exercise 2-5 Odd, the instructions says : return true if the amount of each letter is either an odd value, or zero. Otherwise, return false. Translation : if the length of the string is odd or 0, then return true, else return false. detail for each case : 0, 1, 3, 5, 7 => true 2, 4, 6 => false The test case number 4 has a string of length 7, but for unknown reason expects false... What the hell ?!! Ok, let's imagine that the author made a mistake and forgot to say 7 should return false. After takin...

I have the full version but in the game it says "trial version" and I have access to only the first two chapters. Edit: I am running on Debian Linux on Proton Experimental. Could this be the reason? Edit2: It is also happening on Windows.