_Algorithm Alley: Topological Sorting_
by Jonathan Pincus and Jerry Schwarz


Example 1: 

topsort reports (correctly) that there is a cycle after 1 element
a
cycles reports (correctly) that there are two cycles
cycle 0: g f 
cycle 1: d c b 

topsortWithCycles reports (correctly) that there is a cycle 
a
d
c
b
e
g
f

Example 2: 

template<class RandomAccessIterator,
     class InputIterator,
     class OutputIterator>
int
topsort (RandomAccessIterator begin,
         RandomAccessIterator end,     // members being sorted
         InputIterator beginRel,
         InputIterator endRel,         // relations being sorted
         OutputIterator result
         )