Add days 9 and 10

Author: cema-sp

09.exs

@@ -0,0 +1,185 @@
+defmodule Puzzle do
+  defmodule Group do
+    defstruct [:type, :level, content: ""]
+  end
+
+  def total_score(data) do
+    stats = stream_stats(data)
+    # stats |> IO.inspect(label: "Stats")
+
+    stats.groups
+    |> Enum.filter(&(&1.type == :plain))
+    |> Enum.map(&(&1.level))
+    |> Enum.sum
+  end
+
+  def garbage_chars(data) do
+    stats = stream_stats(data)
+    # stats |> IO.inspect(label: "Stats")
+
+    stats.groups
+    |> Enum.filter(&(&1.type == :garbage))
+    |> Enum.map(&(byte_size(&1.content)))
+    |> Enum.sum
+  end
+
+  @initial_stats %{stack: [], ignore: false, groups: []}
+
+  defp stream_stats(stream, stats \\ @initial_stats)
+  defp stream_stats("", stats), do: stats
+
+  defp stream_stats("!" <> rest, %{ignore: false} = stats) do
+    # IO.puts "Char: !"
+    stream_stats(rest, %{stats | ignore: true})
+  end
+
+  defp stream_stats(<<_char::utf8>> <> rest, %{ignore: true} = stats) do
+    # IO.puts "Ignoring char: #{<<char::utf8>>}"
+    stream_stats(rest, %{stats | ignore: false})
+  end
+
+  defp stream_stats(<<char::utf8>> <> rest, stats) do
+    # IO.puts "Char: #{<<char::utf8>>}"
+
+    {current, stack} = List.pop_at(stats.stack, 0)
+
+    stats =
+      if current && current.type == :garbage do
+        case char do
+          ?> ->
+            # IO.puts "\tClosing garbage group!"
+            %{stats | stack: stack, groups: [current | stats.groups]}
+
+          _ ->
+            # IO.puts "\tContent: #{<<char::utf8>>}"
+            current = %{current | content: current.content <> <<char::utf8>>}
+            %{stats | stack: [current | stack]}
+        end
+      else
+        case char do
+          ?{ ->
+            # IO.puts "\tNew group!"
+            group = %Group{type: :plain, level: next_level(current)}
+            %{stats | stack: [group | [current | stack]]}
+
+          ?} ->
+            # IO.puts "\tClosing group!"
+            %{stats | stack: stack, groups: [current | stats.groups]}
+
+          ?< ->
+            # IO.puts "\tNew garbage group!"
+            group = %Group{type: :garbage, level: next_level(current)}
+            %{stats | stack: [group | [current | stack]]}
+
+          _ ->
+            # IO.puts "\tContent: #{<<char::utf8>>}"
+            current = %{current | content: current.content <> <<char::utf8>>}
+            %{stats | stack: [current | stack]}
+        end
+      end
+
+    stream_stats(rest, stats)
+  end
+
+  defp next_level(nil), do: 1
+  defp next_level(current_group) do
+    current_group.level + 1
+  end
+end
+
+mode = List.first(System.argv)
+
+if mode == "test" do
+  ExUnit.start()
+
+  defmodule PuzzleTest do
+    use ExUnit.Case
+
+    describe "total_score(data) for 1 group" do
+      test "returns expected" do
+        data = "{}"
+        score = Puzzle.total_score(data)
+        assert score == 1
+      end
+    end
+
+    describe "total_score(data) for 3 groups" do
+      test "returns expected" do
+        data = "{{{}}}"
+        score = Puzzle.total_score(data)
+        assert score == 6
+      end
+    end
+
+    describe "total_score(data) for 6 groups" do
+      test "returns expected" do
+        data = "{{{},{},{{}}}}"
+        score = Puzzle.total_score(data)
+        assert score == 16
+      end
+    end
+
+    describe "total_score(data) for 5 groups" do
+      test "returns expected" do
+        data = "{{<ab>},{<ab>},{<ab>},{<ab>}}"
+        score = Puzzle.total_score(data)
+        assert score == 9
+      end
+    end
+
+    describe "total_score(data) for 5 groups with !!" do
+      test "returns expected" do
+        data = "{{<!!>},{<!!>},{<!!>},{<!!>}}"
+        score = Puzzle.total_score(data)
+        assert score == 9
+      end
+    end
+
+    describe "total_score(data) for 2 groups" do
+      test "returns expected" do
+        data = "{{<a!>},{<a!>},{<a!>},{<ab>}}"
+        score = Puzzle.total_score(data)
+        assert score == 3
+      end
+    end
+
+    describe "garbage_chars(data) for 1 group" do
+      test "returns expected" do
+        data = "<>"
+        chars = Puzzle.garbage_chars(data)
+        assert chars == 0
+      end
+    end
+
+    describe "garbage_chars(data) for 1 < group" do
+      test "returns expected" do
+        data = "<<<<>"
+        chars = Puzzle.garbage_chars(data)
+        assert chars == 3
+      end
+    end
+
+    describe "garbage_chars(data) for 1 mixed group" do
+      test "returns expected" do
+        data = "<{o\"i!a,<{i<a>"
+        chars = Puzzle.garbage_chars(data)
+        assert chars == 10
+      end
+    end
+
+    describe "garbage_chars(data) for 1 big group" do
+      test "returns expected" do
+        data = "{{<a!>},{<a!>},{<a!>},{<ab>}}"
+        chars = Puzzle.garbage_chars(data)
+        assert chars == 17
+      end
+    end
+  end
+else
+  data = "09.txt" |> File.read! |> String.trim_trailing
+  score = Puzzle.total_score(data)
+  IO.puts "The total score is: #{score}"
+
+  chars = Puzzle.garbage_chars(data)
+  IO.puts "The number of garbage chars is: #{chars}"
+end