A-M baby

Task/Happy-numbers/Haskell/happy-numbers-1.hs

@@ -0,0 +1,11 @@
+import Data.Char (digitToInt)
+import Data.Set (member, insert, empty)
+
+isHappy :: Integer -> Bool
+isHappy = p empty
+  where p _ 1 = True
+        p s n | n `member` s = False
+              | otherwise  = p (insert n s) (f n)
+        f = sum . map ((^2) . toInteger . digitToInt) . show
+
+main = mapM_ print $ take 8 $ filter isHappy [1..]

Task/Happy-numbers/Haskell/happy-numbers-2.hs

@@ -0,0 +1,10 @@
+import Data.Array
+
+happy x	= if xx <= 150 then seen!xx else happy xx where
+	xx = dsum x
+	seen :: Array Int Bool
+	seen = listArray (1,150) $ True:False:False:False:(map happy [5..150])
+	dsum n	| n < 10 = n * n
+		| otherwise = let (q,r) = n `divMod` 10 in r*r + dsum q
+
+main = print $ sum $ take 10000 $ filter happy [1..]