Problem 63

63.hs

@@ -0,0 +1,11 @@
+digits :: Integer -> Integer
+digits n = 1 + (floor . logBase 10 . fromIntegral $ n)
+
+powerDigits :: Integer -> Integer -> Bool
+powerDigits n p = digits (n ^ p) == p
+
+powers = takeWhile (powerDigits 9) [1..]
+
+count = sum $ map (\n -> sum $ map (\p -> if powerDigits n p then 1 else 0) powers) [1..9]
+
+main = do print count