Day 7

lib/day7.ex

@@ -0,0 +1,73 @@
+defmodule Aoc2023.Day7 do
+  use Aoc2023
+
+  @ranking_1 %{
+    ?A => 13,
+    ?K => 12,
+    ?Q => 11,
+    ?J => 10,
+    ?T => 9,
+    ?9 => 8,
+    ?8 => 7,
+    ?7 => 6,
+    ?6 => 5,
+    ?5 => 4,
+    ?4 => 3,
+    ?3 => 2,
+    ?2 => 1
+  }
+
+  @ranking_2 @ranking_1 |> Map.put(?J, 0)
+
+  def hand_type(values) do
+    for ty <- values, reduce: %{} do
+      m -> Map.update(m, ty, 1, &(&1 + 1))
+    end
+    |> Enum.map(pipe(elem(1)))
+    |> Enum.sort(:desc)
+    |> case do
+      [5] -> 6
+      [4, 1] -> 5
+      [3, 2] -> 4
+      [3, 1, 1] -> 3
+      [2, 2, 1] -> 2
+      [2, 1, 1, 1] -> 1
+      [1, 1, 1, 1, 1] -> 0
+    end
+  end
+
+  def parse(input) do
+    fn rankings, hand_rank ->
+      input
+      |> lines
+      |> Enum.map(&String.split/1)
+      |> Enum.map(fn [hand, bid] ->
+        {
+          hand |> String.to_charlist() |> Enum.map(&Map.get(rankings, &1)),
+          bid |> String.to_integer()
+        }
+      end)
+      |> Enum.sort_by(elem(0) |> hand_rank.() &&& elem(0), :asc)
+      |> Enum.with_index(1)
+      |> Enum.map(fn {{_, bid}, index} -> bid * index end)
+      |> Enum.sum()
+    end
+  end
+
+  def part1(input) do
+    input.(@ranking_1, &hand_type/1)
+  end
+
+  def part2(input) do
+    input.(
+      @ranking_2,
+      fn hand ->
+        @ranking_2
+        |> Enum.map(pipe(elem(1)))
+        |> Enum.map(fn j -> hand |> Enum.map(&if &1 == 0, do: j, else: &1) end)
+        |> Enum.map(&hand_type/1)
+        |> Enum.max()
+      end
+    )
+  end
+end

lib/mix_tasks.ex

@@ -8,6 +8,7 @@ defmodule Mix.Tasks.Aoc do
   defp module(4), do: Aoc2023.Day4
   defp module(5), do: Aoc2023.Day5
   defp module(6), do: Aoc2023.Day6
+  defp module(7), do: Aoc2023.Day7
   # [MODULE INSERTION POINT]  
 
   defp base_dir(), do: System.get_env("AOC_BASE")