31 lines
1.2 KiB
Haskell
31 lines
1.2 KiB
Haskell
import Data.Char
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import Data.List (nub, sort)
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findBegin s@((x,y), c) dict = case filter (\(p,_) -> p == (x,y-1)) dict of
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[] -> s
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n:xs -> findBegin n dict
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uniqueLists :: [[((Int, Int), Char)]] -> [[((Int, Int), Char)]]
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uniqueLists = nub . map sort
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getNumber :: ((Int, Int), Char) -> [String] -> Int
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getNumber ((x,y),c) dict = read (takeWhile isDigit (drop y (dict!!x))) :: Int
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main :: IO ()
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main = do
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inputLines <- lines <$> getContents
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let distances = concat (map (\x -> (map (\y -> (x,y)) [-1..1])) [-1..1])
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let numInputLines = zip [0..] (map (zip [0..]) inputLines)
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let charCoords = concat (map (\(x, l) -> (map (\(y, c) -> ((x,y),c)) l)) numInputLines)
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let gears = map (\(p, c) -> p) (filter (\(_,c) -> c == '*') charCoords)
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let digits = filter (\(_,c) -> isDigit c) charCoords
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let gearsChars = map (\(x,y) -> (filter (\(p,xd) -> (elem p (map (\(x1,y1) -> (x+x1,y+y1)) distances))) digits)) gears
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let gearsBegins = uniqueLists $ map (\gearChars -> (nub (map (\x -> (findBegin x digits)) gearChars))) gearsChars
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let twoGears = filter (\x -> length x == 2) gearsBegins
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let serialNumbers = map (\gs -> product $ map (\g -> getNumber g inputLines) gs) twoGears
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print (sum serialNumbers)
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