Day 11 - part 1.

app/Main.hs

@@ -30,4 +30,4 @@ import qualified Day24
 import qualified Day25
 
 main :: IO ()
-main = Day10.main
+main = Day11.main

src/Day11.hs

@@ -1,6 +1,23 @@
 module Day11 (main) where
 
+import Data.Char (digitToInt)
+import Data.List (maximumBy)
+import Data.Ord (comparing)
+
+indexToCoord :: Int -> (Int, Int)
+indexToCoord i = (1 + i `div` 300, 1 + i `mod` 300)
+
+powerLevel :: (Int, Int) -> Int
+powerLevel (x, y) = (subtract 5) . digitToInt . (!! 2) . reverse . show $ ((x + 10) * y + 7672) * (x + 10)
+
+powerSquare :: Int -> (Int, Int) -> Int
+powerSquare size (x, y) =
+    if   x > 300 - size + 1 || y > 300 - size + 1 then -5
+    else sum [powerLevel (x', y') | x' <- [x .. x + size - 1], y' <- [y .. y + size - 1]]
+
+part1 :: (Int, Int)
+part1 = indexToCoord . fst . maximumBy (comparing snd) . zip [0..] . map (powerSquare 3 . indexToCoord) $ [0 .. 300 * 300]
+
 main :: IO ()
 main = do
-    input <- readFile "input/11.txt"
+    print part1
-    print input