blog/files/algorithms/time-complexity/extend/construction.dot

digraph G {
    node [shape=record];

    a_node [label="1|2|3|4|5|6|7|8|9"]

    b_node [label="1|2|3"]
    c_node [label="4|5|6"]
    d_node [label="7|8|9"]

    a_node -> b_node [label="B"]
    a_node -> c_node [label="C"]
    a_node -> d_node [label="D"]

    b_node -> "1"
    b_node -> "2"
    b_node -> "3"

    c_node -> "4"
    c_node -> "5"
    c_node -> "6"

    d_node -> "7"
    d_node -> "8"
    d_node -> "9"
}