Problem 19
http://projecteuler.net/index.php?section=problems&id=19
--Haskell, 20090101 zeller :: Int -> Int -> Int zeller y m = if (y + y`div`4 - y`div`100 + y`div`400 + (13*m+8)`div`5 + 1) `mod` 7 == 0 then 1 else 0 main = print $ sum $ map (sum . flip map [3..14] . zeller) [1901..2000]