66 lines
1.8 KiB
Haskell
66 lines
1.8 KiB
Haskell
{-# LANGUAGE OverloadedStrings #-}
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module AoC.Day3 where
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import Data.Text (Text)
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import Data.Maybe (fromMaybe)
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import Data.Monoid (Sum(..), getSum)
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import Data.List.Split (chunksOf)
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import Data.Tuple.Extra (uncurry3)
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import qualified Data.Text as T
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valueMap :: [(Char, Int)]
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valueMap = zip (['a'..'z']++['A'..'Z']) [1..]
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breakInTwoEqualLengthSubStrings :: Text -> (Text,Text)
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breakInTwoEqualLengthSubStrings txt = T.splitAt (T.length txt `div` 2) txt
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findCommonItem :: Text -> Text -> Char
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findCommonItem _ "" = undefined
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findCommonItem compartment1 compartment2 =
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if (c `T.elem` compartment1)
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then c
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else findCommonItem compartment1 (T.tail compartment2)
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where
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c = T.head compartment2
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solveAOnOne :: Text -> Int
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solveAOnOne = fromMaybe undefined
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. flip lookup valueMap
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. uncurry findCommonItem
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. breakInTwoEqualLengthSubStrings
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solveA :: Text -> Int
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solveA = getSum . mconcat . map (Sum . solveAOnOne) . T.lines
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--------------------------------------------------------------------------------
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-- Part 2
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findCommonItem3 :: Text -> Text -> Text -> Char
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findCommonItem3 c1 c2 c3 = T.head $ go (go c1 c2) c3
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where
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go :: Text -> Text -> Text
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go t1 = T.foldl (\acc c -> if c `T.elem` t1 then T.cons c acc else acc) ""
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tupleMeUp3 :: [[Text]] -> [(Text,Text,Text)]
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tupleMeUp3 = go []
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where
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go :: [(Text,Text,Text)] -> [[Text]] -> [(Text,Text,Text)]
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go tuples [] = tuples
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go tuples ([t1, t2, t3]:xs) = go ((t1,t2,t3):tuples) xs
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go _ _ = undefined
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solveBOnOne :: (Text,Text,Text) -> Int
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solveBOnOne = fromMaybe undefined
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. flip lookup valueMap
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. uncurry3 findCommonItem3
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solveB :: Text -> Int
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solveB = getSum
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. mconcat
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. map (Sum . solveBOnOne)
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. tupleMeUp3
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. chunksOf 3
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. T.lines
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