1 PROCEDURE (G=(L1, L2, E): two-layered graph, C=( L2xL2: acyclic constraints)
 2     Let V be a set of vertices that have constraints;
 3     Let V’ be a set of vertices that do not have constraints
 4     L(u) <- {}; //Empty list
 5     CALL computeBaryCenter with G Return L(u)
 6     Add all pair constrained (u, v) to V
 7     Add vertices that do not have constraints to V'
 9     WHILE (u,v) = find_violate_constraint(V,C) is not empty
10         create new dummy vertex vc
11         deg(vc) = deg(u) + deg(v)
12         b(vc) = (b(u ) * deg(u ) + b(v) * deg(v)) / deg(vc)
13         L(vc) = L(u) × L(v)
14         //Add incident edges of u or v to vc
15         FOR each c in C
16            IF c is incident to u or v
17              make c incident to vc
18            ENDIF
19         END LOOP
20         Remove any self loop from C
21         Remove (u,v) from V.
22         IF vc has incident constraint THEN
23            Add vc into V
24         ELSE
25            Add vc into V’
26         ENDIF
27         Add both set V and V' to V''
28         Sort V’’ by barycentric values
29         Empty the temporary list L
30        //Concatenate and replace dummy vertices by the
31        //original vertices
32        FOR each v in V’’
33          Concatenate vertices into a list L
34        END LOOP
35     ENDWHILE
37 END PROCEDURE