42 lines
1.2 KiB
Haskell
42 lines
1.2 KiB
Haskell
{-# LANGUAGE LambdaCase #-}
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{-# LANGUAGE MultiWayIf #-}
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module Main where
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import Data.Functor
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data Rotation where
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RRight :: Int -> Rotation
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RLeft :: Int -> Rotation
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parse :: String -> [Rotation]
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parse = map (\case
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('R':xs) -> RRight (read xs :: Int)
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('L':xs) -> RLeft (read xs :: Int)
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_ -> error "") . lines
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solver :: Bool -> [Rotation] -> Int
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solver b = go 50
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where go :: Int -> [Rotation] -> Int
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go _ [] = 0
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go curr (RRight n : xs) =
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let (rots,newCurr) = bound (curr + n) in
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(if | b -> (rots+)
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| newCurr == 0 -> (1+)
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| otherwise -> id) $ go newCurr xs
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go curr (RLeft n : xs) =
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let (rots,newCurr) = bound (curr - n) in
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(if | b -> (rots+)
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| newCurr == 0 -> (1+)
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| otherwise -> id) $ go newCurr xs
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bound :: Int -> (Int,Int)
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bound x
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| x < 0 = (\(n,y) -> (n+1,y)) . bound $ x + 100
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| x > 99 = (\(n,y) -> (n+1,y)) . bound $ x - 100
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| otherwise = (0, x)
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main :: IO ()
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main = readFile "inputs/1" <&> parse >>= \i ->
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print (solver False i) >>
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print (solver True i)
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