54 lines
1.6 KiB
Haskell
Executable File
54 lines
1.6 KiB
Haskell
Executable File
#! /usr/bin/env -S"ANSWER=42" nix-shell
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#! nix-shell -p ghcid
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#! nix-shell -p "haskellPackages.ghcWithPackages (p: with p; [pretty-simple attoparsec])"
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#! nix-shell -i "ghcid -c 'ghci' -T main"
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{-# OPTIONS_GHC -Wall -Wincomplete-uni-patterns #-}
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{-# OPTIONS_GHC -Wno-unused-top-binds -Wno-unused-imports #-}
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{-# OPTIONS_GHC -Wno-unused-matches -Wno-type-defaults #-}
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{-# LANGUAGE OverloadedStrings #-}
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import Control.Applicative
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import Data.Attoparsec.Text (Parser)
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import Data.Text (Text)
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import Debug.Trace (trace)
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import Text.Pretty.Simple
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import Data.Maybe (fromMaybe,catMaybes)
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import Data.List (find,sortOn)
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import qualified Data.Attoparsec.Text as A
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import qualified Data.Text as T
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exampleData :: String
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exampleData = "939\n7,13,x,x,59,x,31,19"
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numOrXParser :: Parser (Maybe Int)
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numOrXParser = (Just <$> A.decimal) <|> ("x" *> pure Nothing)
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inputParser :: Parser (Int,[Int])
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inputParser = do
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n <- A.decimal
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A.skipSpace
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xs <- numOrXParser `A.sepBy` ","
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pure (n,catMaybes $ xs)
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parseInput :: String -> Either String (Int,[Int])
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parseInput = (A.parseOnly inputParser) . T.pack
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solvePart1 :: String -> Either String Int
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solvePart1 str = do
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(n,xs) <- parseInput str
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let (bus, time) = head
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$ sortOn (snd)
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$ map (\x -> (x,fromMaybe (-1) $ find (> n) [0,x..])) xs
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pure $ bus * (time - n)
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main :: IO ()
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main = do
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putStrLn ":: Test"
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pPrint $ A.parseOnly inputParser $ T.pack exampleData
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pPrint $ take 3 ((\n -> [1,n..]) 59)
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putStrLn ":: Day 13 - Part 1"
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input <- readFile "day13/input"
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pPrint $ solvePart1 exampleData
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pPrint $ solvePart1 input
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