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module Solutions.Day14
open System
open System.IO
let lineToCoords (line: string) =
line.Split([|","; " -> "|], StringSplitOptions.None)
|> Array.map int
|> Array.chunkBySize 2
|> Array.map (fun x -> x[0], x[1])
let coordsToPointSet (coords: (int * int) array) =
let coordLine (x1, y1) (x2, y2) =
seq { for x in min x1 x2 .. max x1 x2 do for y in min y1 y2 .. max y1 y2 -> (x, y) }
|> Set.ofSeq
Array.fold2 (fun points coord1 coord2 -> coordLine coord1 coord2 |> Set.union points) Set.empty coords[..Array.length coords - 2] coords[1..]
let cave = File.ReadAllLines("inputs/day14.txt") |> Array.map (lineToCoords >> coordsToPointSet) |> Set.unionMany
let startPoint = (500, 0)
let rec watch abyss (cave, p1) =
let rec drop cave p1 (x, y) =
[ x, y+1; x-1, y+1; x+1, y+1]
|> Seq.tryFind (fun n -> not (Set.contains n cave))
|> (function
| None -> Set.add (x, y) cave, p1
| Some (nx, ny) when ny = abyss ->
Set.add (nx, ny) cave,
(if p1 = -1 then Set.count cave else p1)
| Some n -> drop cave p1 n)
if Set.contains startPoint cave then
(p1, Set.count cave)
else
watch abyss (drop cave p1 startPoint)
let solution =
let abyss = (cave |> Seq.maxBy snd |> snd) + 1
let r = Set.count cave
let rns = watch abyss (cave, -1)
(fst rns - r), (snd rns - r)
let part1 () = fst solution
let part2 () = snd solution
|