From a7ef2ed5435d4c8fae26dfa5f9937c1d5daeb5f4 Mon Sep 17 00:00:00 2001
From: Adam Ruzicka <aru@cosmic.voyage>
Date: Sat, 2 Dec 2023 14:16:13 +0100
Subject: [PATCH] 2023 day 2 in Haskell

---
 2023/02/day2.hs | 68 +++++++++++++++++++++++++++++++++++++++++++++++++
 2023/02/example |  5 ++++
 2 files changed, 73 insertions(+)
 create mode 100644 2023/02/day2.hs
 create mode 100644 2023/02/example

diff --git a/2023/02/day2.hs b/2023/02/day2.hs
new file mode 100644
index 0000000..3f30b97
--- /dev/null
+++ b/2023/02/day2.hs
@@ -0,0 +1,68 @@
+{-# LANGUAGE OverloadedStrings #-}
+
+import Data.Text qualified as T
+import Text.Printf (printf)
+
+type Set = (Integer, Integer, Integer)
+
+type Game = (Integer, [Set])
+
+emptySet = (0, 0, 0)
+
+part1 :: [Game] -> Integer
+part1 = sum . map fst . filter (all setWithinLimits . snd)
+
+part2 :: [Game] -> Integer
+part2 = sum . map (setPower . minimumSet . snd)
+
+minimumSet :: [Set] -> Set
+minimumSet ss = (maximum $ map first ss, maximum $ map second ss, maximum $ map third ss)
+  where
+    first (r, _, _) = r
+    second (_, g, _) = g
+    third (_, _, b) = b
+
+setWithinLimits (r, g, b) = r <= 12 && g <= 13 && b <= 14
+
+parseGame :: T.Text -> Game
+parseGame s = (parseId $ head parts, parseSets $ last parts)
+  where
+    parts = T.splitOn ":" s
+
+parseId :: T.Text -> Integer
+parseId = read . T.unpack . last . T.words
+
+parseSets :: T.Text -> [Set]
+parseSets = map parseSet . T.splitOn ";"
+
+parseSet :: T.Text -> Set
+parseSet = sumSets . map parseDraw . T.splitOn ","
+
+addSets :: Set -> Set -> Set
+addSets (r1, g1, b1) (r2, g2, b2) = (r1 + r2, g1 + g2, b1 + b2)
+
+sumSets :: [Set] -> Set
+sumSets = foldl addSets emptySet
+
+setPower :: Set -> Integer
+setPower (r, g, b) = r * g * b
+
+parseDraw :: T.Text -> Set
+parseDraw s = setOf count color
+  where
+    setOf n "red" = (n, 0, 0)
+    setOf n "green" = (0, n, 0)
+    setOf n "blue" = (0, 0, n)
+    parts = T.words s
+    color = last parts
+    count = read $ T.unpack $ head parts
+
+parseInput :: T.Text -> [Game]
+parseInput = map parseGame . T.lines
+
+main :: IO ()
+main = do
+  contents <- getContents
+  let parsed = parseInput $ T.pack contents
+  putStr $ printf "Part 1: %d\n" $ part1 parsed
+  putStr $ printf "Part 2: %d\n" $ part2 parsed
diff --git a/2023/02/example b/2023/02/example
new file mode 100644
index 0000000..295c36d
--- /dev/null
+++ b/2023/02/example
@@ -0,0 +1,5 @@
+Game 1: 3 blue, 4 red; 1 red, 2 green, 6 blue; 2 green
+Game 2: 1 blue, 2 green; 3 green, 4 blue, 1 red; 1 green, 1 blue
+Game 3: 8 green, 6 blue, 20 red; 5 blue, 4 red, 13 green; 5 green, 1 red
+Game 4: 1 green, 3 red, 6 blue; 3 green, 6 red; 3 green, 15 blue, 14 red
+Game 5: 6 red, 1 blue, 3 green; 2 blue, 1 red, 2 green