Day7

Day 7: No Space Left On Device

Day 7: No Space Left On Device

Part 1

input = """
$ cd /
$ ls
dir a
14848514 b.txt
8504156 c.dat
dir d
$ cd a
$ ls
dir e
29116 f
2557 g
62596 h.lst
$ cd e
$ ls
584 i
$ cd ..
$ cd ..
$ cd d
$ ls
4060174 j
8033020 d.log
5626152 d.ext
7214296 k
"""

f = fn
  "$ cd ..", map, current, paths ->
    {map, Enum.slice(current, 0..-2), paths}

  "$ cd " <> dir, map, current, paths ->
    new_current = current ++ [dir]
    new_paths = MapSet.put(paths, new_current)

    case get_in(map, new_current) do
      nil ->
        new_map = put_in(map, new_current, %{files: [], total_size: 0})
        {new_map, new_current, new_paths}

      %{files: _files} ->
        {map, current, new_paths}
    end

  "$ ls", map, current, paths ->
    {map, current, paths}

  "dir " <> _dir, map, current, paths ->
    {map, current, paths}

  line, map, current, paths ->
    file_name = line |> String.split(" ") |> Enum.at(-1)
    file_size = line |> String.split(" ") |> Enum.at(0) |> String.to_integer()
    files_path = current ++ [:files]
    total_size_path = current ++ [:total_size]

    {_, new_map} =
      get_and_update_in(map, files_path, &{&1, &1 ++ [{file_name, file_size}]})
      |> elem(1)
      |> get_and_update_in(total_size_path, &{&1, &1 + file_size})

    {new_map, current, paths}
end

{map, _, paths} =
  input
  |> String.split("\n", trim: true)
  |> Enum.reduce({%{}, [], MapSet.new()}, fn line, {acc_map, acc_current, acc_paths} ->
    f.(line, acc_map, acc_current, acc_paths)
  end)

IO.inspect(map)
IO.inspect(paths)

total_sizes =
  paths
  |> Enum.reduce(%{}, fn path, acc ->
    key = Enum.join(path, "/")
    total_size = get_in(map, path ++ [:total_size])
    Map.update(acc, key, total_size, fn _ -> :error end)
  end)

IO.inspect(total_sizes)

sum_of_total_sizes =
  paths
  |> Enum.reduce(%{}, fn path, acc ->
    key = Enum.join(path, "/")

    sum_of_total_size =
      total_sizes
      |> Enum.filter(fn {path, _total_size} -> String.starts_with?(path, key) end)
      |> Enum.map(fn {_path, total_size} -> total_size end)
      |> Enum.sum()

    Map.update(acc, key, sum_of_total_size, fn _ -> :error end)
  end)

sum_of_total_sizes
|> Enum.filter(fn {_path, sum_of_total_size} -> sum_of_total_size <= 100_000 end)
|> IO.inspect()
|> Enum.map(fn {_path, sum_of_total_size} -> sum_of_total_size end)
|> Enum.sum()

Part 2

f = fn
  "$ cd ..", map, current, paths ->
    {map, Enum.slice(current, 0..-2), paths}

  "$ cd " <> dir, map, current, paths ->
    new_current = current ++ [dir]
    new_paths = MapSet.put(paths, new_current)

    case get_in(map, new_current) do
      nil ->
        new_map = put_in(map, new_current, %{files: [], total_size: 0})
        {new_map, new_current, new_paths}

      %{files: _files} ->
        {map, current, new_paths}
    end

  "$ ls", map, current, paths ->
    {map, current, paths}

  "dir " <> _dir, map, current, paths ->
    {map, current, paths}

  line, map, current, paths ->
    file_name = line |> String.split(" ") |> Enum.at(-1)
    file_size = line |> String.split(" ") |> Enum.at(0) |> String.to_integer()
    files_path = current ++ [:files]
    total_size_path = current ++ [:total_size]

    {_, new_map} =
      get_and_update_in(map, files_path, &{&1, &1 ++ [{file_name, file_size}]})
      |> elem(1)
      |> get_and_update_in(total_size_path, &{&1, &1 + file_size})

    {new_map, current, paths}
end

{map, _, paths} =
  input
  |> String.split("\n", trim: true)
  |> Enum.reduce({%{}, [], MapSet.new()}, fn line, {acc_map, acc_current, acc_paths} ->
    f.(line, acc_map, acc_current, acc_paths)
  end)

IO.inspect(map)
IO.inspect(paths)

total_sizes =
  paths
  |> Enum.reduce(%{}, fn path, acc ->
    key = Enum.join(path, "/")
    total_size = get_in(map, path ++ [:total_size])
    Map.update(acc, key, total_size, fn _ -> :error end)
  end)

IO.inspect(total_sizes)

sum_of_total_sizes =
  paths
  |> Enum.reduce(%{}, fn path, acc ->
    key = Enum.join(path, "/")

    sum_of_total_size =
      total_sizes
      |> Enum.filter(fn {path, _total_size} -> String.starts_with?(path, key) end)
      |> Enum.map(fn {_path, total_size} -> total_size end)
      |> Enum.sum()

    Map.update(acc, key, sum_of_total_size, fn _ -> :error end)
  end)

unused_space = 70_000_000 - sum_of_total_sizes["/"]

sum_of_total_sizes
|> Enum.filter(fn {_path, sum_of_total_size} -> unused_space + sum_of_total_size >= 30_000_000 end)
|> IO.inspect()
|> Enum.min_by(fn {_path, sum_of_total_size} -> sum_of_total_size end)
|> IO.inspect()
|> elem(1)