60 lines
1.5 KiB
Haskell
60 lines
1.5 KiB
Haskell
import Control.Exception (assert)
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import Data.Bits (bit)
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import Data.Char (digitToInt)
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import Data.List (group, maximumBy, minimumBy, sort,
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transpose)
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import Data.Ord (comparing)
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main :: IO ()
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main = do
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diagnostics <- getContents
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putStrLn (solution1 diagnostics)
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solution1 :: String -> String
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solution1 diagnostics = show (calcGamma * calcEpsilon)
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where
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calcGamma = listToBit (map most (parseDiagnostics diagnostics))
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calcEpsilon = listToBit (map least (parseDiagnostics diagnostics))
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parseDiagnostics :: String -> [[Int]]
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parseDiagnostics diagnostics = map (map digitToInt) (transpose (lines diagnostics))
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most :: [Int] -> Int
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most = head . (maximumBy (comparing length)) . group . sort
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least :: [Int] -> Int
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least = head . (minimumBy (comparing length)) . group . sort
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listToBit :: [Int] -> Int
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listToBit list = foldr (\b acc -> (acc + toBit b)) 0 (enumerate (reverse list))
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where
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-- Takes a location and value to converts it to the appropriate
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-- integer.
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toBit :: (Int, Int) -> Int
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toBit (i, b) = if b == 1
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then bit i
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else 0
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enumerate :: [a] -> [(Int, a)]
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enumerate = zip [0..]
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-- Tests
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testInput1 :: String
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testInput1 = unlines [
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"00100",
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"11110",
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"10110",
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"10111",
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"10101",
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"01111",
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"00111",
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"11100",
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"10000",
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"11001",
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"00010",
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"01010"
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]
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test1 :: String
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test1 = assert ((solution1 testInput1) == "198") "success"
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