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56 lines
1.5 KiB
56 lines
1.5 KiB
module Main where |
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import Debug.Trace |
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import System.Environment (getArgs) |
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main :: IO () |
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main = do |
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input <- readFile . head =<< getArgs |
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print $ part1 input |
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print $ part2 input |
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part1 :: String -> Int |
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part1 = sum . filter invalid . concat . map ids . map parse . splitOn ',' |
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splitOn :: (Eq a) => a -> [a] -> [[a]] |
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splitOn delim xs = case dropWhile (== delim) xs of |
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[] -> [] |
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s' -> xs' : splitOn delim s'' |
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where |
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(xs', s'') = break (== delim) s' |
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parse :: String -> (Int, Int) |
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parse = group . map read . splitOn '-' |
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where |
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group :: (Show a) => [a] -> (a, a) |
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group (x : y : []) = (x, y) |
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group x = error $ "group: " ++ show x ++ "is not two elements" |
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ids :: (Int, Int) -> [Int] |
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ids (start, end) = [start .. end] |
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invalid :: Int -> Bool |
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invalid i = |
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let s = show i |
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len = length s |
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half = take (len `div` 2) s |
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in s == half ++ half |
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part2 :: String -> Int |
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part2 = sum . filter invalid2 . concat . map ids . map parse . splitOn ',' |
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invalid2 :: Int -> Bool |
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invalid2 i = |
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let s = show i |
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len = length s |
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facs = factors len |
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in or [(repeatN (len `div` n) $ take n s) == s | n <- facs] |
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-- needs to get the primes instead of all factors |
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factors :: Int -> [Int] |
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factors i = filter ((== 0) . (mod i)) [1 .. i `div` 2] |
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repeatN :: Int -> [a] -> [a] |
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repeatN i = concat . replicate i |
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testInput = "11-22,95-115,998-1012,1188511880-1188511890,222220-222224,1698522-1698528,446443-446449,38593856-38593862,565653-565659,824824821-824824827,2121212118-2121212124"
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