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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
|