| Input: graph , sink |
| Output: subproblem set |
| (1) return if is a tree; |
| (2) let be the minimum directed cycle found by the DICIRCUIT algorithm in [13]; |
| (3) if then // no cycle |
| (4)find any vertex with out degree larger than 1, and |
| insert its out edges into ; |
| (5) ; |
| (6) foreach do |
| (7); |
| (8)reverse the direction of edges in , and perform a breadth-first search from the sink; |
| (9)if all vertices are visited then |
| (10); |
| (11)construct subproblem with as the network; |
| (12) if then |
| (13) graph of subproblem ; |
| (14)return ; |
| (15) else |
| (16)return ; |