60 lines
2.1 KiB
Haskell
60 lines
2.1 KiB
Haskell
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import Data.List.Split
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import Data.Matrix
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import Data.Maybe
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type Value = Integer
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data IsVisited = Visited | Unvisited deriving (Eq, Show)
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type Position = (Int, Int)
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data Element = Element Value IsVisited Position deriving (Eq, Show)
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getUnvisitedNeighbours :: Matrix Element -> Element -> [Element]
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getUnvisitedNeighbours m (Element _ _ (i, j)) =
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filter (\(Element _ isVisited _) -> isVisited == Visited)
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(catMaybes [safeGet (i - 1) j m
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,safeGet (i + 1) j m
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,safeGet i (j - 1) m
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,safeGet i (j + 1) m])
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getNeighbourDistances :: Element -> [Element] -> [Element]
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getNeighbourDistances e = map (addValue e)
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where addValue (Element ve isVisited _) (Element vn _ p) = Element (ve + vn) isVisited p
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getMin :: Value -> Value -> Value
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getMin v1 0 = v1
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getMin 0 v2 = v2
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getMin v1 v2 = min v1 v2
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dijkstraMatrix :: Matrix Element -> (Value, Position)
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dijkstraMatrix m =
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let neighbourDistanceMatrix = fmap (\e -> getNeighbourDistances e (getUnvisitedNeighbours m e)) m
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-- fold over Visited with getMin
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in (0, (0, 0))
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-- for unvisited element in matrix
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-- for unvisited neighbour of element
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-- if element value + neighbour value < min then set as min
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-- return min; default is (0, (0, 0))
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nextMatrix :: Matrix Element -> Matrix Element
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nextMatrix m =
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let (minValue, position) = dijkstraMatrix m
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maybeMatrix = safeSet (Element minValue Visited position) position m
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in case maybeMatrix of
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Just next -> next
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Nothing -> m
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initElement :: Matrix Integer -> Position -> Element
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initElement m p =
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let value = m ! p
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in Element value Unvisited p
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toElementMatrix :: Matrix Integer -> Matrix Element
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toElementMatrix m =
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matrix (nrows m) (ncols m) (initElement m)
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main :: IO ()
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main = do
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contents <- readFile "p081_matrix.txt"
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let listsMatrix = map (map read . (splitOn ",")) $ lines contents :: [[Integer]]
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valueMatrix = fromLists listsMatrix
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mtrx = toElementMatrix valueMatrix
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print mtrx
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