dfs_test.exs

# To run: `elixirc dfs.ex && elixir dfs_test.exs`
IO.inspect(Dfs.visit(1, [
    {1,  [2, 7, 8]},
    {2,  [1, 3, 6]},
    {3,  [2, 4, 5]},
    {4,  [3]},
    {5,  [3]},
    {6,  [2]},
    {7,  [1]},
    {8,  [1, 9, 12]},
    {9,  [8, 10, 11]},
    {10, [9]},
    {11, [9]},
    {12, [8]}
]))