31 lines
957 B
Haskell
31 lines
957 B
Haskell
module Main (main) where
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import Control.Monad (when)
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import Data.List (foldl')
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import System.Exit (die)
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exampleExpectedOutput = 127
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parseInput :: String -> IO [Int]
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parseInput filename = do
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input <- readFile filename
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return $ map read $ lines input
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validate :: [Int] -> Int -> Bool
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validate list n = processInput list
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where
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processInput :: [Int] -> Bool
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processInput (_:[]) = False
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processInput (x:xs) = (foldl' (\acc i -> acc || (x + i == n && x /= i)) False xs) || processInput xs
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compute :: Int -> [Int] -> Int
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compute len list
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| validate (take len list) (list !! len) = compute len $ tail list
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| otherwise = list !! len
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main :: IO ()
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main = do
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example <- parseInput "example"
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let exampleOutput = compute 5 example
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when (exampleOutput /= exampleExpectedOutput) (die $ "example failed: got " ++ show exampleOutput ++ " instead of " ++ show exampleExpectedOutput)
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input <- parseInput "input"
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print $ compute 25 input
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