digraph G{
START [label="START"];
A1 [label="A"];
A2 [label="A"];
A3 [label="A"];
B1 [label="B"];
B2 [label="B"];
C1 [label="C"];
C2 [label="C"];
END [label="END"]
START->A1
A1->B1
A1->C1
B1->A2
C1->A2
A2->B2
A2->C2
B2->A3
C2->A3
A3->END
}
这与@rakwaht已经建议并且你已经接受的完全相同,只是更加简洁地书写 - 我不认为这是一场噩梦:
digraph G{
START [label="START"];
A1, A2, A3 [label="A"];
B1, B2 [label="B"];
C1, C2 [label="C"];
END [label="END"];
START-> A1 -> { B1 C1 } -> A2 -> { B2 C2 } -> A3 -> END
}