day 7

Signed-off-by: Amneesh Singh <natto@weirdnatto.in>

day07.hs

@@ -0,0 +1,62 @@
+import Data.Char (ord)
+import Data.List (group, nub, sort, sortBy)
+import Data.Ord (comparing)
+import Data.Text qualified as T
+import Lib (count)
+
+-- yes, this is slow
+-- i dont have time for a cuter (and faster) answer :<
+-- Update: I found a solution on reddit that uses some cool default GHC extensions and is much faster, i am not going to use it, but feel free to look it up
+main :: IO ()
+main = do
+  input' <- map words . lines <$> readFile "day07.in"
+  let bids = map (\[x, y] -> (x, read y)) input'
+
+  putStr "Q1: "
+  print
+    . sum
+    . zipWith (*) [1 ..]
+    . map snd
+    . sortBy (comparing (handKind . fst) <> comparing (map strength . fst))
+    $ bids
+
+  putStr "Q2: "
+
+  print
+    . sum
+    . zipWith (*) [1 ..]
+    . map snd
+    . sortBy
+      ( comparing
+          (\(hand, _) -> maximum [handKind (map repl hand) | x <- nub hand, let repl c = if c == 'J' then x else c])
+          <> comparing (map strength2 . fst)
+      )
+    $ bids
+
+strength :: Char -> Int
+strength c = case c of
+  'A' -> 13
+  'K' -> 12
+  'Q' -> 11
+  'J' -> 10
+  'T' -> 9
+  _ -> ord c - ord '1'
+
+strength2 :: Char -> Int
+strength2 c = case c of
+  'A' -> 13
+  'K' -> 12
+  'Q' -> 11
+  'J' -> 0
+  'T' -> 9
+  _ -> ord c - ord '1'
+
+handKind :: String -> Int
+handKind hand = case sort $ map length $ group $ sort hand of
+  [5] -> 6
+  [1, 4] -> 5
+  [2, 3] -> 4
+  [1, 1, 3] -> 3
+  [1, 2, 2] -> 2
+  [1, 1, 1, 2] -> 1
+  _ -> 0