45 lines
1.3 KiB
Haskell
45 lines
1.3 KiB
Haskell
{-# LANGUAGE LambdaCase #-}
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module Main where
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import Data.Functor
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import Data.Matrix hiding (trace)
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import Data.List
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import Debug.Trace
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import Data.Maybe
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parse :: String -> Matrix Char
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parse = fromLists . lines
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getGroup :: (Int,Int) -> Matrix Char -> [(Int,Int)]
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getGroup (i,j) s =
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let e = getElem i j s in
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go e [(i,j)] []
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where go :: Char -> [(Int,Int)] -> [(Int,Int)] -> [(Int,Int)]
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go _ [] v = v
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go c (x@(i,j):xs) v
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| x `elem` v = go c xs v
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| uncurry safeGet x s /= Just c = go c xs v
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| otherwise = go c (filter (isJust . flip (uncurry safeGet) s) [(i+1,j),(i-1,j),(i,j+1),(i,j-1)] ++ xs) (x:v)
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groups :: Matrix Char -> [[(Int,Int)]]
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groups s = go [(i,j) | i <- [1 .. nrows s], j <- [1 .. ncols s]] []
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where go :: [(Int,Int)] -> [[(Int,Int)]] -> [[(Int,Int)]]
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go [] v = v
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go (x:xs) v
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| any (x `elem`) v = go xs v
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| otherwise = go xs (nub (getGroup x s):v)
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perimeter :: [(Int,Int)] -> Int
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perimeter s = length $ s >>= \(i,j) -> [(i,j+1),(i,j-1),(i+1,j),(i-1,j)] \\ s
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solve1 :: Matrix Char -> Int
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solve1 s = let g = groups s; p = perimeter <$> g in sum $ zipWith (*) (length <$> g) p
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solve2 :: Matrix Char -> Int
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solve2 = undefined
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main :: IO ()
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main = readFile "inputs/12" <&> parse >>= \i ->
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print (solve1 i) >>
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print (solve2 i)
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