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Ingy döt Net 2023-07-01 11:58:00 -04:00
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commit cb5bb5e222
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Task/Iterated-digits-squaring/Haskell/iterated-digits-squaring.hs Normal file
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import Data.List (unfoldr)
import Data.Tuple (swap)
step :: Int -> Int
step = sum . map (^ 2) . unfoldr f where
f 0 = Nothing
f n = Just . swap $ n `divMod` 10
iter :: Int -> Int
iter = head . filter (`elem` [1, 89]) . iterate step
main = do
print $ length $ filter ((== 89) . iter) [1 .. 99999999]