Fix bug that made greed consider empty non-string lists as having one item

In SRM 596 div1 500, there was an issue with the test cases. It is an unusual problem that has long[] arguments and return and the arrays are allowed to be empty. Greed was rendering an empty long array as {LL}. It turns out that greed parsed non-string empty arrays wrong, thinking that they have a single element equal to an empty string. This should fix that issue.