12 lines
322 B
Haskell
12 lines
322 B
Haskell
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digits :: Integer -> Integer
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digits n = 1 + (floor . logBase 10 . fromIntegral $ n)
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powerDigits :: Integer -> Integer -> Bool
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powerDigits n p = digits (n ^ p) == p
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powers = takeWhile (powerDigits 9) [1..]
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count = sum $ map (\n -> sum $ map (\p -> if powerDigits n p then 1 else 0) powers) [1..9]
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main = do print count
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