> module Main where > input = "aaaabbbcca" > r :: String -> (Char,Int) -> [(String, Int)] > r [] (c,n) = [([c],n)] > r (x:xs) (c,n) > | c == x = r xs (c,n

> module Main where > input = "aaaabbbcca" > r :: String -> (Char,Int) -> [(String, Int)] > r [] (c,n) = [([c],n)] > r (x:xs) (c,n) > | c == x = r xs (c,n+1) > | otherwise = (([c],n): r xs (x,1)) > main = putStrLn (show (r (tail input) (head input, 1) )) 4 minutes 42 seconds. And no, I don't write code like this normally, but I guess this is me when I'm under time pressure... anyway, I could refactor it nicely afterwards in the 25 minutes allocated.