java 8, to pass case 11

    long combinations = 0;
    // countries with one astronaut
    long countriesWithOne = N - graph.getAllNodes().size();

    // all other countries with more than one astronauts 
    List<Integer> countries = graph.mapRegions();

    for (int i = 0; i < countries.size(); i++) {
        for (int j = i + 1; j < countries.size(); j++) {
            combinations += countries.get(i) * countries.get(j); 
        }
        combinations += countries.get(i) * countriesWithOne;
    }

    combinations += (countriesWithOne * (countriesWithOne - 1)) / 2;

    System.out.println(combinations);