42 lines
1.1 KiB
Haskell
42 lines
1.1 KiB
Haskell
main :: IO ()
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main = readFile "2/input.txt" >>= print . solve . parse . lines
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parse :: [String] -> [Instruction]
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parse = map (parseLine . words)
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solve :: [Instruction] -> (Int,Int)
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solve input = (f input, g input)
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where f = uncurry (*) . simulate Abs
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g = uncurry (*) . simulate (Aim 0)
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data Nav = Aim Int
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| Abs
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data Instruction = Forward Int
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| Down Int
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| Up Int
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parseLine :: [String] -> Instruction
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parseLine [ s, x ]
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| s == "forward" = Forward n
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| s == "down" = Down n
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| s == "up" = Up n
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where
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n = read x
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simulate :: Nav -> [Instruction] -> (Int,Int)
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simulate nav = iter nav (0,0)
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iter :: Nav -> (Int,Int) -> [Instruction] -> (Int,Int)
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iter _ r [] = r
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iter Abs (x,y) (i:is) = case i of
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Forward n -> iter Abs (x+n,y)
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Down n -> iter Abs (x,y+n)
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Up n -> iter Abs (x,y-n)
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$ is
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iter (Aim a) (x,y) (i:is) = case i of
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Forward n -> iter (Aim a) (x+n,y+(a*n))
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Down n -> iter (Aim (a+n)) (x,y)
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Up n -> iter (Aim (a-n)) (x,y)
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$ is
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