57 lines
2.7 KiB
Haskell
57 lines
2.7 KiB
Haskell
module Part2 where
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import Commons
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import Data.Array (assocs, bounds, (//))
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getReachableOdd :: Garden -> Int
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getReachableOdd garden =
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let ((yMin, xMin), (yMax, xMax)) = bounds garden
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n = (yMax - yMin + div (yMax - yMin) 2)
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newGarden = garden // [((1 + div (yMax - yMin) 2, 1 + div (xMax - xMin) 2), Plot {reachable = True})]
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in length $ getReachableAfterNMove n newGarden
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getReachableEven :: Garden -> Int
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getReachableEven garden =
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let ((yMin, xMin), (yMax, xMax)) = bounds garden
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n = (yMax - yMin + 1 + div (yMax - yMin) 2)
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newGarden = garden // [((1 + div (yMax - yMin) 2, 1 + div (xMax - xMin) 2), Plot {reachable = True})]
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in length $ getReachableAfterNMove n newGarden
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getReachableCardinals :: Garden -> [Int]
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getReachableCardinals garden =
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let ((yMin, xMin), (yMax, xMax)) = bounds garden
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n = yMax - yMin
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(yMean, xMean) = (1 + div (yMax - yMin) 2, 1 + div (xMax - xMin) 2)
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in [length $ getReachableAfterNMove n $ garden // [((yMean, xMin), Plot {reachable = True})],
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length $ getReachableAfterNMove n $ garden // [((yMean, xMax), Plot {reachable = True})],
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length $ getReachableAfterNMove n $ garden // [((yMin, xMean), Plot {reachable = True})],
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length $ getReachableAfterNMove n $ garden // [((yMax, xMean), Plot {reachable = True})]]
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getReachableOddCorners :: Garden -> [Int]
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getReachableOddCorners garden =
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let ((yMin, xMin), (yMax, xMax)) = bounds garden
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n = yMax - yMin + div (yMax - yMin) 2
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in [length $ getReachableAfterNMove n $ garden // [((yMin, xMin), Plot {reachable = True})],
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length $ getReachableAfterNMove n $ garden // [((yMin, xMax), Plot {reachable = True})],
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length $ getReachableAfterNMove n $ garden // [((yMax, xMin), Plot {reachable = True})],
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length $ getReachableAfterNMove n $ garden // [((yMax, xMax), Plot {reachable = True})]]
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getReachableEvenCorners :: Garden -> [Int]
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getReachableEvenCorners garden =
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let ((yMin, xMin), (yMax, xMax)) = bounds garden
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n = div (yMax - yMin) 2 - 1
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in [length $ getReachableAfterNMove n $ garden // [((yMin, xMin), Plot {reachable = True})],
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length $ getReachableAfterNMove n $ garden // [((yMin, xMax), Plot {reachable = True})],
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length $ getReachableAfterNMove n $ garden // [((yMax, xMin), Plot {reachable = True})],
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length $ getReachableAfterNMove n $ garden // [((yMax, xMax), Plot {reachable = True})]]
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getReachableAfterN :: Int -> Garden -> Int
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getReachableAfterN n garden =
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let ((yMin, xMin), (yMax, xMax)) = bounds garden
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x = div (n - div (yMax - yMin) 2) (yMax - yMin + 1)
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in x * x * getReachableEven garden + x * sum (getReachableEvenCorners garden)
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+ (x - 1) * (x - 1) * getReachableOdd garden + (x - 1) * sum (getReachableOddCorners garden)
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+ sum (getReachableCardinals garden)
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