This one is a bit weird, in that it uses your eyes to solve it. The solution comes in two parts

go run main.go inputfile dot

will get you a DOT representation of the graph. If you pipe this into neato, you can visually see the separation.

You then input the nodes to "cut" into the cut subcommand. For instance, this is how you would execute the sample

go run main.go inputfile cut htj,pcc dlk,pjj bbg,htb

Here is an example SVG of the sample input, to demonstrate how you would pick out "htj-pcc", "dlk-pjj", "bbg-htb"