From c500a9a280090f60f84127850e700404212ab4f4 Mon Sep 17 00:00:00 2001
From: bluepython508 <bluepython508@users.noreply.github.io>
Date: Thu, 7 Dec 2023 12:12:31 +0000
Subject: [PATCH] Improvements to day 7

---
 lib/day7.ex | 61 ++++++++++++++++++++++++-----------------------------
 1 file changed, 27 insertions(+), 34 deletions(-)

diff --git a/lib/day7.ex b/lib/day7.ex
index 3685dbd..7ced72f 100644
--- a/lib/day7.ex
+++ b/lib/day7.ex
@@ -1,28 +1,14 @@
 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
+    values
+    |> Enum.frequencies()
+    |> then(fn freq ->
+      {jokers, freq_} = freq |> Map.pop(0, 0)
+      common = freq_ |> Enum.max_by(pipe(elem(1))) |> elem(0)
+      freq_ |> Map.update!(common, &(&1 + jokers))
+    end)
     |> Enum.map(pipe(elem(1)))
     |> Enum.sort(:desc)
     |> case do
@@ -37,7 +23,7 @@ defmodule Aoc2023.Day7 do
   end
 
   def parse(input) do
-    fn rankings, hand_rank ->
+    fn rankings ->
       input
       |> lines
       |> Enum.map(&String.split/1)
@@ -47,27 +33,34 @@ defmodule Aoc2023.Day7 do
           bid |> String.to_integer()
         }
       end)
-      |> Enum.sort_by(elem(0) |> hand_rank.() &&& elem(0), :asc)
+      |> Enum.sort_by(elem(0) |> hand_type &&& elem(0), :asc)
       |> Enum.with_index(1)
       |> Enum.map(fn {{_, bid}, index} -> bid * index end)
       |> Enum.sum()
     end
   end
 
+  @ranking [
+    ?2,
+    ?3,
+    ?4,
+    ?5,
+    ?6,
+    ?7,
+    ?8,
+    ?9,
+    ?T,
+    ?J,
+    ?Q,
+    ?K,
+    ?A,
+  ] |> Enum.with_index(1) |> Map.new
+
   def part1(input) do
-    input.(@ranking_1, &hand_type/1)
+    input.(@ranking)
   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
-    )
+    input.(@ranking |> Map.put(?J, 0))
   end
 end