36 lines
1.5 KiB
Haskell
36 lines
1.5 KiB
Haskell
module Part1 where
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import Commons
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import Data.Array ((!))
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getDistanceToStart :: (Int, Int) -> Direction -> Grid -> Int
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getDistanceToStart (y, x) South grid =
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case grid ! (y, x) of
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Pipe (North, South) -> 1 + getDistanceToStart (y + 1, x) South grid
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Pipe (North, East) -> 1 + getDistanceToStart (y, x + 1) East grid
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Pipe (North, West) -> 1 + getDistanceToStart (y, x - 1) West grid
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Start -> 0
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getDistanceToStart (y, x) West grid =
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case grid ! (y, x) of
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Pipe (East, West) -> 1 + getDistanceToStart (y, x - 1) West grid
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Pipe (North, East) -> 1 + getDistanceToStart (y - 1, x) North grid
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Pipe (South, East) -> 1 + getDistanceToStart (y + 1, x) South grid
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Start -> 0
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getDistanceToStart (y, x) North grid =
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case grid ! (y, x) of
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Pipe (North, South) -> 1 + getDistanceToStart (y - 1, x) North grid
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Pipe (South, East) -> 1 + getDistanceToStart (y, x + 1) East grid
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Pipe (South, West) -> 1 + getDistanceToStart (y, x - 1) West grid
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Start -> 0
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getDistanceToStart (y, x) East grid =
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case grid ! (y, x) of
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Pipe (East, West) -> 1 + getDistanceToStart (y, x + 1) East grid
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Pipe (North, West) -> 1 + getDistanceToStart (y - 1, x) North grid
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Pipe (South, West) -> 1 + getDistanceToStart (y + 1, x) South grid
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Start -> 0
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getCycleLength :: Grid -> Int
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getCycleLength grid = let (dir, startCoords) = getStartDirection (getStartCoordinates grid) grid
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in 1 + getDistanceToStart startCoords dir grid
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