src/advent11/advent11-map.hs

   1 {-# LANGUAGE OverloadedStrings #-}
   2
   3 import Data.List
   4 import qualified Data.Map.Strict as M
   5 -- import Data.Map.Strict ((!))
   6 -- import qualified Data.Set as S
   7 -- import Data.Function (on)
   8 import Data.Ord (comparing)
   9
  10 type Coord = (Integer, Integer) -- x, y
  11 type Grid = M.Map Coord Integer
  12
  13 key = 5719
  14 -- key = 42
  15
  16 main :: IO ()
  17 main = do
  18         let g = makeGrid key
  19         print $ part1 g
  20         print $ part2 g
  21
  22
  23 part1 grid = keyOfMaxValue sg
  24     where sg = allSubCellPower 3 grid
  25
  26
  27 part2 grid = maximumBy (comparing snd) $ [bestInGrid size grid | size <- [3..300]]
  28
  29 -- bestSubCell size grid =
  30
  31 makeGrid :: Integer -> Grid
  32 makeGrid key = M.fromList [((x, y), powerLevel x y key) | x <- [1..300], y <- [1..300] ]
  33
  34 powerLevel :: Integer -> Integer -> Integer -> Integer
  35 powerLevel x y key = ((interim `div` 100) `mod` 10) - 5
  36     where rackID = x + 10
  37           interim = ((rackID) * y + key) * rackID
  38
  39 subCellPower :: Integer -> Integer -> Integer -> Grid -> Integer
  40 subCellPower size x y grid = M.foldr (+) 0 subGrid
  41     where subGrid = M.filterWithKey inBounds grid
  42           inBounds (kx, ky) _ = (kx >= x) && (kx < x+size) && (ky >= y) && (ky < y+size)
  43
  44 allSubCellPower :: Integer -> Grid -> Grid
  45 allSubCellPower size grid = M.fromList [((x, y), subCellPower size x y grid)| x <- [1..(301-size)], y <- [1..(301-size)]]
  46
  47
  48 keyAndMaxValue :: Ord b => M.Map a b -> (a, b)
  49 keyAndMaxValue m = M.foldrWithKey mergeKV (M.findMin m) m
  50     where mergeKV k v (bestK, bestV) =
  51             if v > bestV then (k, v) else (bestK, bestV)
  52
  53 keyOfMaxValue :: Ord b => M.Map a b -> a
  54 keyOfMaxValue m = fst $ keyAndMaxValue m
  55
  56 bestInGrid :: Integer -> Grid -> ((Integer, Integer, Integer), Integer)
  57 bestInGrid size grid = ((x, y, size), p)
  58     where ((x, y), p) = keyAndMaxValue $ allSubCellPower size grid