Could you post your code (with a spoiler tag)?

Me either, tried diffrent approach - works in Ide, throws runtime error here.

It is indeed. But as you said: excersise.

In order to clarify:

JS version:

Time: 8729ms Passed: 104 Failed: 0
Test Results:
  Basic Tests
  It should works for basic tests. (4 Passed, 0 Failed)
 Completed in 8ms
  100 Random Tests --- Testing for correctness of solution
  It should works for random tests. (100 Passed, 0 Failed)
 Completed in 8214ms
  Congratulations! You have passed all the tests!
 Log
 I'm waiting for your feedback, rank and vote.many thanks! ;-) 

C# version:

Time: 10341ms Passed: 2 Failed: 0
Test Results:
  myjinxin.CsharpTest
  Test1__Basic_Tests (1 Passed, 0 Failed)
  Test2__100_Random_Tests (1 Passed, 0 Failed)
You have passed all tests! :)

Python version:

Time: 2591ms Passed: 104 Failed: 0
Test Results:
  Basic Tests (4 Passed, 0 Failed)
  100 Random Tests (100 Passed, 0 Failed)

One thing you need to know is that if the author's code fails to pass the test, kata cannot be published ;-)

im not so sure about that... Ive managed to get the basic examples down to a 30ms return yet i still cant get the server to reach 100 tests on a full atempt.

I think the random tests is OK ;-)
You need to improve the performance of your code.