1 PROCEDURE (G: digraph)
 2 Let s1 be an empty list //Source
 3 Let s2 be an empty list //Sink
 4 WHILE G is not empty
 5     WHILE G contains a sink
 6       Choose a sink u
 7       Insert u to s2
 8       Remove u from G
 9     END WHILE
10
11     WHILE G contains a source
12       Choose a source v;
13       Append v to s1
14       Remove v from G
15     ENDWHILE
16
17 //If there are vertices with both
18 //incoming and outgoing edges,
19 //compute the difference between outdegree
20 //and indegree.
21 //Find the vertex with largest delta
22 //and append to s1
23     IF G not empty
24       Compute delta(u):delta(u) = outdeg(u) – indeg(u)
25       Choose a vertex u such as delta(u) is maximum
26       Append u to s1
27       Remove u and all its incident edges from G
28     ENDIF
29
30 ENDWHILE
31 //Concatenate S2 to S1 to form S, a vertex sequence
32 COMPUTER S by CONCATENATING S2 into S1 to form S
33
34 END PROCEDURE