Project Euler 解答

Project Euler Problem 082

Project Euler Problem 082

import Data.List
import System.IO.Unsafe
ss :: [[Integer]]
ss = map (\x -> read ("["++x++"]")::[Integer]) $ lines $ unsafePerformIO $ readFile "082matrix.txt"
initss :: [a] -> [[a]]
initss = tail . inits
cands :: [Integer] -> [Integer] -> [[Integer]]
cands acc rights= zipWith (:) acc (initss rights)
mcand :: [Integer] -> [Integer] -> Integer
mcand a r = minimum $ map sum $ cands a r
min3 :: Integer -> Integer -> Integer -> Integer
min3 = ((min.).min) :: Integer -> Integer -> Integer -> Integer
sol :: [Integer] -> [Integer] -> [Integer]
sol aa@(a:b:bs) bb@(x:y:ys)=
    v1 : imp ([a],b,bs) ([x],y,ys) where
     v1 = mcand aa bb
     imp :: ([Integer],Integer,[Integer]) ->([Integer],Integer,[Integer]) ->[Integer]
     imp (al,up,[]) (l,x,[]) =
       [val] where
         val = x + (min up (mcand al l))
     imp (al,up,[a]) (l,x,[r]) =
       val : imp (up:al,a,[]) (x:l,r,[]) where
         val = x + (min3 up (mcand al l) (a+r))
     imp (al,up,(a:ar)) (l,x,(r:rs)) =
       val : imp (up:al,a,ar) (x:l,r,rs) where
         val = x + (min3 up (mcand al l) (mcand (a:ar) (r:rs)))
ans1 :: Integer
ans1 = minimum $ foldl1 sol (transpose ss)

-- 260324
main :: IO ()
main = print ans1

since 2013