Don't be trapped by the title of this problem...it would just make it more complicated

I see no problem in the title. It's a very simple straight forward TOP_SORT problem. And I have seen some critical cases in other threads which cases would appear 'critical' if and only if any process other than simple top_sort is approached.

I`d say don`t be trapped by the category of the problem. It says Graph Theory, but can be easily solved with other data structures.