Skip to content

Instantly share code, notes, and snippets.

Embed
What would you like to do?
import Data.Array.IO
import Control.Monad (forM_)
import System.Time
import System.IO
type IData = Int
-- slow but simple load (better avoiding intermediate list)
readWeights :: IO (IOUArray (Int, Int) IData)
readWeights = do
c <- getContents
let a :: [IData]
a = read c
s = (floor.sqrt.fromIntegral.length) a - 1
newListArray ((0, 0), (s, s)) a
main = do
w <- readWeights
putStrLn "Computing distances..."
t0 <- getClockTime
((_, _), (b, _)) <- getBounds w
let r = [0..b]
-- can be parallelized!!!
forM_ r $ \k -> do
forM_ r $ \x -> do
forM_ r $ \y -> do
xk <- readArray w (x, k)
ky <- readArray w (k, y)
xy <- readArray w (x, y)
writeArray w (x, y) $ min xy (xk + ky)
t1 <- getClockTime
if b < 40
then
forM_ [0..b] $ \x -> do
forM_ [0..b] $ \y -> do
readArray w (x, y) >>= putStr . (++ ", ") . show
putStrLn "|"
else
return ()
putStrLn ("Time: " ++ show (diffClockTimes t1 t0))
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment