31 lines
910 B
Haskell
31 lines
910 B
Haskell
{-# LANGUAGE ScopedTypeVariables #-}
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import Data.List
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main = do
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lines <- readFile "3.in"
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putStrLn . show . solve . (!!0) . words $ lines
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where
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solve = length . Data.List.group . Data.List.sort . partB
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-- solves all lines, returns a string
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partA :: [Char] -> [(Int, Int)]
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partA = getPositions
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where
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getPositions = snd . foldl updatePosition ((0,0), [(0,0)]) . map coords
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-- updatePosition :: b -> a -> b
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updatePosition ((x, y), positions) (a, b) = ((x + a, y + b), (x + a, y + b):positions)
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-- (right, up)
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coords '>' = (1, 0)
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coords '<' = (-1, 0)
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coords 'v' = (0, -1)
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coords '^' = (0, 1)
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coords _ = (0, 0)
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partB :: [Char] -> [(Int, Int)]
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partB l = id =<< [ partA . odds $ l, partA . evens $ l]
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where
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evens = odds . tail
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odds [] = []
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odds [x] = [x]
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odds (x:y:r) = x:(odds r)
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