tree.dot

digraph g {
    n1 [label = "10"];
    n2 [label = "7"];
    n3 [label = "2"];
    n4 [label = "5"];
    n5 [label = "6"];
    n6 [label = "3"];
    n7 [label = "7"];
    n1 -> n2;
    n1 -> n3;
    n2 -> n4;
    n2 -> n5;
    n3 -> n6;
    n3 -> n7;
}