@hobovsky, but 6, 4, 6, 6, 4 is not going to be 400 in any way. Three 6 is 600. Why was he expecting 400?

As I said, without knowing your code, it is difficult to tell. There can be so many possible causes, that to know for sure, I would have to run your solution, and see how tests behave. There is really, really many things which can go wrong, and in languages like C or C++ your solution can even make error messages wrong. And we do not even know the language, so we have absolutely zero idea what to check. If you give us your code, we will know the broken language, and we will be able to run broken tests, see why they fail, and tell you how to fix your broken solution.

Could it be, you're mutating the input?

My guess is, you're using a global var and it keeps the previous vale.

How can we know? :) We cannot tell without knowing your code.