Hello,

I'm trying to solve Euler problem 104 with the solution "My Solution" below but it takes quite long time therefore I quite.

Then I turn to haskell wiki for better solution which work well but I can not figure out why it is better than mine.

I'm wondering whether more function call decrease the performance.

Could you please help a little?

Thank you.

-- | My Solution

main = print $ snd $ head $ dropWhile (\(x,y) -> (not . bothNinePandigit "123456789") x) (zip fibs [1..])

bothNinePandigit digits n = isFirstNinePandigit digits n && isLastNinePandigit digits n

isLastNinePandigit digits n = digits == sort (lastDigits 9 n)

isFirstNinePandigit digits n = digits == sort (firstDigits 9 n)

firstDigits k n = take k (show n)

lastDigits k n = show (n `mod` 10^k)

fibs = 0 : 1 : zipWith (+) fibs (tail fibs)

-- | From Haskell Wiki

fibs = 1 : 1 : zipWith (+) fibs (tail fibs)

isFibPan n =

let a = n `mod` 1000000000

b = sort (show a)

c = sort $ take 9 $ show n

in b == "123456789" && c == "123456789"

ex_104 = snd $ head $ dropWhile (\(x,y) -> (not . isFibPan) x) (zip fibs [1..])