Day 11 part 1

It's slow again

day11/input

@@ -0,0 +1,93 @@
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+.LL...............L..L.L.LL...L.LL.....LL..L.LL.L.L...L.......L..L.LL..L.L...LL...L...............
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day11/main.hs

@@ -0,0 +1,130 @@
+#! /usr/bin/env -S"ANSWER=42" nix-shell
+#! nix-shell -p ghcid
+#! nix-shell -p "haskellPackages.ghcWithPackages (p: with p; [pretty-simple vector])"
+#! nix-shell -i "ghcid -c 'ghci' -T main"
+
+{-# OPTIONS_GHC -Wall -Wincomplete-uni-patterns #-}
+{-# OPTIONS_GHC -Wno-unused-top-binds -Wno-unused-imports -Wno-type-defaults #-}
+{-# OPTIONS_GHC -Wno-unused-matches #-}
+{-# LANGUAGE OverloadedStrings #-}
+
+import Data.Maybe (catMaybes)
+import Data.Function (fix)
+import Data.Vector (Vector)
+import Debug.Trace (trace,traceShow)
+import Text.Pretty.Simple
+import qualified Data.Vector as V
+
+exampleData :: [String]
+exampleData =
+  [ "L.LL.LL.LL"
+  , "LLLLLLL.LL"
+  , "L.L.L..L.."
+  , "LLLL.LL.LL"
+  , "L.LL.LL.LL"
+  , "L.LLLLL.LL"
+  , "..L.L....."
+  , "LLLLLLLLLL"
+  , "L.LLLLLL.L"
+  , "L.LLLLL.LL"
+  ]
+
+type Width = Int
+type Pos   = Int
+
+data State = StateEmpty | StateSeatFree | StateSeatOccupied
+  deriving (Eq, Ord)
+
+instance Show State
+  where
+    show StateEmpty         = "."
+    show StateSeatFree      = "L"
+    show StateSeatOccupied  = "#"
+
+type SeatLayout = Vector State
+
+drawSeatLayout :: Width -> SeatLayout -> String
+drawSeatLayout w s = concat $ V.toList $ V.imap go s
+  where
+    go i s0 = show s0 ++ if (i `mod` w) == (w - 1) then "\n" else ""
+
+parseInput :: String -> SeatLayout
+parseInput = V.fromList . (map go)
+  where
+    go '.' = StateEmpty
+    go 'L' = StateSeatFree
+    go '#' = StateSeatOccupied
+    go c   = trace (c:" is undefined") undefined
+
+fStep :: Width -> SeatLayout -> SeatLayout
+fStep w s = if f s == s then s else fStep w (f s)
+  where
+    f = step w
+
+step :: Width -> SeatLayout -> SeatLayout
+step w s = V.imap go s
+  where
+    -- If a seat is empty (L) and there are no occupied seats adjacent to it,
+    -- the seat becomes occupied.
+    go i StateSeatFree =
+      if all (== StateSeatFree) $ filter (/= StateEmpty) $ neighbors i
+      then StateSeatOccupied
+      else StateSeatFree
+    -- If a seat is occupied (#) and four or more seats adjacent to it are also
+    -- occupied, the seat becomes empty.
+    go i StateSeatOccupied =
+      if ( (length . (filter (== StateSeatOccupied))) (neighbors i) ) >= 4
+      then StateSeatFree
+      else StateSeatOccupied
+    -- Otherwise, the seat's state does not change.
+    -- ie the rest remains as-is.
+    go _ state = state
+
+    -- Build a list of neighbors
+    neighbors :: Pos -> [State]
+    neighbors p = catMaybes [
+        -- 1: east
+        s V.!? toP (i+1,j)
+        -- 2: west
+      , s V.!? toP (i-1,j)
+        -- 3: north
+      , s V.!? toP (i,j-1)
+        -- 4: south
+      , s V.!? toP (i,j+1)
+        -- 5: north east
+      , s V.!? toP (i+1,j-1)
+        -- 6: north west
+      , s V.!? toP (i-1,j-1)
+        -- 7: south east
+      , s V.!? toP (i+1,j+1)
+        -- 8: south west
+      , s V.!? toP (i-1,j+1)
+      ]
+      where
+        toP (i0,j0) | i0 < w && i0 >= 0 = j0 * w + i0
+        toP (i0,j0) | otherwise         = -1
+        (i,j) = (p `mod` w, p `div` w)
+
+solvePart1 :: String -> Int
+solvePart1 str =  length
+                $ V.filter (== StateSeatOccupied)
+                $ fStep w
+                $ parseInput
+                $ concat
+                $ lines
+                $ str
+  where
+    w = length $ head $ lines $ str
+
+main :: IO ()
+main = do
+  putStrLn ":: Tests"
+  putStrLn $ drawSeatLayout 10 $ fStep 10 $ parseInput $ concat exampleData
+  putStrLn ":: Day 11 - Part 1"
+  print $ solvePart1 $ unlines exampleData
+  input <- readFile "day11/input"
+  print $ 2329 -- print $ solvePart1 input
+  putStrLn ":: Tests"
+
+  putStrLn ":: Day 11 - Part 2"
+

template.hs

@@ -4,7 +4,7 @@
 #! nix-shell -i "ghcid -c 'ghci' -T main"
 
 {-# OPTIONS_GHC -Wall -Wincomplete-uni-patterns #-}
-{-# OPTIONS_GHC -Wno-unused-top-binds -Wno-unused-imports #-}
+{-# OPTIONS_GHC -Wno-unused-top-binds -Wno-unused-imports -Wno-type-defaults #-}
 {-# LANGUAGE OverloadedStrings #-}
 
 import Debug.Trace (trace)