Hi, I participating in de google code jam this year and I want to try to use haskell. The following simple http://code.google.com/codejam/contest/dashboard?c=90101#s=p2 problem would have the beautiful haskell solution. import Data.MemoTrie import Data.Char import Data.Word import Text.Printf newtype ModP = ModP Integer deriving Eq p=10000 instance Show ModP where show (ModP x) = printf "%04d" x instance Num ModP where ModP x + ModP y = ModP ((x + y) `mod` p) fromInteger x = ModP (x `mod` p) ModP x * ModP y = ModP ((x * y) `mod` p) abs = undefined signum = undefined solve _ [] = 1::ModP solve [] _ = 0::ModP solve (hs:ts) t@(ht:tt) | hs==ht = solve ts tt + solve ts t | otherwise = solve ts t go (run, line) = "Case #"++show run++": "++show (solve line "welcome to code jam") main = interact $ unlines . map go . zip [1..] . tail . lines Which is unfortunately exponential. Now in earlier thread I argued for a compiler directive in the lines of {-# Memoize function -#}, but this is not possible (it seems to be trivial to implement though). Now I used memotrie which runs hopelessly out of memory. I looked at some other haskell solutions, which were all ugly and more clumsy compared to simple and concise C code. So it seems to me that haskell is very nice and beautiful until your are solving real algorithmic problems when you want to go back to some imperative language. How would experienced haskellers solve this problem? Thanks -- View this message in context: http://www.nabble.com/memoization-tp25306687p25306687.html Sent from the Haskell - Haskell-Cafe mailing list archive at Nabble.com.