graphviz中节点的垂直对齐

我试图制作一个{C1；C2}垂直对齐的图。与{A；B；C}和{E1；E2；E3}相同

以下是我目前的代码：

digraph G{
    rankdir="LR";
    S -> C1 [label="150"];
    S -> C2 [label="130"];
    C1 -> A [label="70"];
    C1 -> B [label="80"];
    C2 -> B [label="60"];
    C2 -> C [label="70"];
    C -> B [label="10"];
    A -> E1 [label="70"];
    B -> E1 [label="80"];
    B -> D [label="70"];
    C -> E3 [label="60"];
    D -> E1 [label="40"];
    D -> E2 [label="0"];
    D -> E3 [label="30"];
    E1 -> t [label="190"];
    E2 -> t [label="0"];
    E3 -> t [label="90"];
}

以下是迄今为止的结果：

---

{rank=same；}

是你的朋友。我在A、B和C之间添加了不可见的边，以使它们更紧密地结合在一起，并反转了一个连接，以使A比B比C更紧密，等等

digraph G
{
    rankdir="LR";
    { rank = same; C1 C2 }
    { rank = same; A -> B -> C[ style = invis ] }
    { rank = same; E1 E2 E3 }
    S -> C1 [label="150"];
    S -> C2 [label="130"];
    C1 -> A [label="70"];
    C1 -> B [label="80"];
    C2 -> B [label="60"];
    C2 -> C [label="70"];
    B -> C [dir = back, label="10"];   // to keep B above C
    A -> E1 [label="70"];
    B -> E1 [label="80"];
    B -> D [label="70"];
    C -> E3 [label="60"];
    D -> E1 [label="40"];
    D -> E2 [label="0"];
    D -> E3 [label="30"];
    E1 -> t [label="190"];
    E2 -> t [label="0"];
    E3 -> t [label="90"]; 
}

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