euler solution

yihuang · Nov 18, 2011 · 52d6045 · 52d6045
1 parent d345232
commit 52d6045
Showing 1 changed file with 7 additions and 0 deletions.
diff --git a/euler12.hs b/euler12.hs
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+tris :: [Int]
+tris = 1 : 3 : zipWith (\a b -> b + b - a + 1) tris (tail tris)
+
+divisors :: Int -> Int
+divisors n = (*) 2 $ (+) 1 $ length . filter (\x -> n `rem` x == 0) $ [2 .. (floor . sqrt . fromIntegral $ n)]
+
+main = print $ head . filter ((>500) . divisors) $ tris