Can i speed up a algoritm when i use int.MaxValue and i had only 5,1 sec? but here i have always more than 12 sec?

Thanks for answer. I forgot about it.

Your solution does exactly the thing which is described in description as too slow.

Two years and no answer. Closing.

I also have that issue with that runtime over 1200ms.

By the way, the times presented at testresult are incorrect, on top it says 502ms and below it says 0.5ms.

Your solution returns incorrect answer for n=143.
A solution being incorrect is not a kata issue.

My all test past but when i try atemp my solution i had 2 errors.

Test Failed
Expected string length 9 but was 12. Strings differ at index 5.
Expected: "[5, 2][4]"
But was: "[5, 2, 1][0]"
----------------^

This is a poorly written test. My solution is correct and there is a wrong string calculation on the test...