AMCAT Test Issue.

Have you guys ( Amazon specially ) found any issues while Online test with AMcat?. Not dying to get into Amazon but its been 2 times I failed their online test because of Amcat test platform Last time, their java priority queue wasnt able to sort the inputs. This time, simple TreeMap wasnt working. Both the times, I was able to run the same code with my local java environment successfully and both the times second of the 2 test question failed for Amcat as the only reason.