43 lines
1.3 KiB
Haskell
43 lines
1.3 KiB
Haskell
{-# LANGUAGE OverloadedStrings #-}
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module Day2 where
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import System.IO (openFile, IOMode (ReadMode), hClose, hGetContents)
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import Data.Text (splitOn, Text, unpack, pack)
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data Submarine = Submarine {
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horizontal :: Int
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, depth :: Int
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} deriving Show
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type Movement = (String, Int)
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-- "forward 5" -> ("forward", 5)
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parseInstruction :: String -> Movement
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parseInstruction instr = (kind, magnitude)
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where
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split = map unpack $ splitOn " " $ pack instr
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kind = head split
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magnitude = read $ split !! 1
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move :: Submarine -> Movement -> Submarine
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move sub ("forward", magnitude) = sub { horizontal = horizontal sub + magnitude }
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move sub ("down", magnitude) = sub { depth = depth sub + magnitude }
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move sub ("up", magnitude) = sub { depth = depth sub - magnitude }
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(++) :: Submarine -> Submarine -> Submarine
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x ++ y = Submarine { horizontal = horizontal x + horizontal y, depth = depth x + depth y }
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main :: IO ()
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main = do
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input <- openFile "inputs/2.txt" ReadMode
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contents <- hGetContents input
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let submarine = Submarine { horizontal = 0, depth = 0 }
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let instructions = parseInstruction <$> lines contents
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let sub = foldl move submarine instructions
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print $ horizontal sub * depth sub
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hClose input |