public static ArrayList<String> findAnimalHipsters(HashMap<String, ArrayList<String>> network,
            HashMap<String, String> favoriteAnimals) {
        ArrayList<String> tmp = new ArrayList<String>();
        ArrayList<String> buff;
        int count = 0;
        for (String key : network.keySet()) {
            buff = network.get(key);
            for (String s : buff) {
                if (favoriteAnimals.get(s).equalsIgnoreCase(favoriteAnimals.get(key)))
                    count++;
            }
            if (count == 0)
                tmp.add(key);
            count = 0;
        }
        return (tmp == null) ? null : tmp;
    }