solution for day 12

1 files changed, 48 insertions, 0 deletions

diff --git a/solutions/day12.fs b/solutions/day12.fs
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+module Solutions.Day12
+open System.IO
+open AStar
+
+let input = File.ReadAllLines("inputs/day12.txt") |> Array.map Array.ofSeq
+
+let findPoint ch =
+    let row = Array.findIndex (Array.contains ch) input
+    let col = Array.findIndex (fun x -> x = ch) input[row]
+    (row, col)
+
+let startCoord, endCoord = findPoint 'S', findPoint 'E'
+input[fst startCoord][snd startCoord] <- 'a'
+input[fst endCoord][snd endCoord] <- 'z'
+
+let height, width = input.Length, input[0].Length
+
+let neighbors (row, col) =
+    [|(row-1, col); (row+1, col); (row, col-1); (row, col+1)|]
+    |> Seq.filter (fun (nRow, nCol) -> nRow >= 0 && 
+                                       nRow < height && 
+                                       nCol >= 0 && 
+                                       nCol < width &&
+                                       input[nRow][nCol] <= input[row][col] + char 1)
+
+let gScore _ _ = 1.0
+
+let fScore (x, y) (dx, dy) =
+    sqrt ((float dx - float x) ** 2.0 + (float dy - float y) ** 2.0)
+
+let getPathLength start finish =
+    match search start finish {neighbours = neighbors; gCost = gScore; fCost = fScore; maxIterations = None} with
+    | Some path -> Seq.length path - 1
+    | None -> -1
+
+let part1 () =
+    getPathLength startCoord endCoord    
+
+let part2 () = 
+    seq {
+        for row in 0 .. height - 1 do
+        for col in 0 .. width - 1 do
+        if input[row][col] = 'a' then 
+            getPathLength (row, col) endCoord
+    }
+    |> Seq.filter (fun x -> x > 0)
+    |> Seq.sort
+    |> Seq.head