FlipMatrix.hs

import qualified Data.Vector as V

main :: IO ()
main = do
    n <- readLn
    replicateM_ n $ do
        (n, m) <- readMatrix
        print (bestQuadrant n m)

type Matrix = V.Vector (V.Vector Int)

readMatrix :: IO (Int, Matrix)
readMatrix = do
    n <- readLn
    m <- V.replicateM (2 * n) (V.fromList . map read . words  getLine)
    pure (n, m)

bestQuadrant :: Int -> Matrix -> Int
bestQuadrant n m =
    let symetries x = [x, 2 * n - 1 - x]
    in sum $ do
        i <- [0 .. n-1]
        j <- [0 .. n-1]
        pure $ maximum $ do
            x <- symetries i
            y <- symetries j
            pure (m V.! x V.! y)