Still not fixed.

I just used long doubles and regular round() function. Solution is literally a 1-line one.

std::sort performs comparision based sort, which cannot have worst case algorithmic time complexity lower than O(n*log(n))

Is there even an O(n) solution to this problem? :)

'Helloworld' = true 
'Helloworld ' = false
           ^ because of this

I would like to elaborate but going into details would be giving the solution; it would not be fair. Please read again the description and examine carefully the drawing.

BTW thanks!

It is possible because we don't have to calculate this kind of numbers.
Be sure that there are no errors in the tests.
Moreover it is a question not an issue. Sorry for your usual problems with my kata:-( Cheers.

You can modify the function header.

Not an issue of the kata (passed by more than 6000 people).

No one is obligated to help you. This attitude can work in real life but not in internet. Stop being rude.

Sorry but asking for help is not an issue. Cheers.

It's a bug in the kata setup. You need to include cstring (not string.h) header file in your solution to make it work.

swap out the #include <string> for #include <string.h>

It is true because if you change the middle character c (you have to change one), you still get a palindrome.

Already reported here and still not fixed :(

Include cstring or string.h (depending on whether you are using C++ or C) in your solution, should help.

And leave this issue open, maybe the author will finally get to fixing it.