Advent of Coed 2020 day 21 in F#

aoc2020day21.fsx

#time "on"

let lines = System.IO.File.ReadAllLines ( __SOURCE_DIRECTORY__ + "/input.txt")

let pars (l: string array) =
    l 
    |> Array.map(fun line -> 
        let [|f; a|] = line.Split("(")
        f.Trim().Split(" ") |> Array.toList, a.TrimEnd(')').Split(" ") 
        |> Array.map(fun s -> s.TrimEnd(',')) |> Array.tail |> Array.toList)

    |> Array.toList

let menu = pars lines

let allergenes = menu |> List.collect snd |> List.distinct
let aMap =
    allergenes |> List.map(fun allergene ->
        allergene, 
        menu 
        |> List.filter (snd >> fun a -> a |> List.contains(allergene))
        |> List.map (fst >> Set.ofList)
    )

let hasAllergenes =
    aMap 
    |> List.map(fun a -> a |> snd |> Set.intersectMany)
    |> List.reduce (+)


let allIngrediences = menu |> List.collect fst |> Set.ofList
let noAllergs = allIngrediences - hasAllergenes

let count = menu |> List.collect fst |> List.filter (fun i -> Set.contains i noAllergs) |> List.length

printfn "part1: %d" count

//part 2
let hasAllergenes2 =
    aMap 
    |> List.map(fun (a, i) -> a,  i |> Set.intersectMany)

let rec find (foundI:Set<string>) HA Aout =
    let HA' = HA |> List.map(fun (a, i ) -> a, i - foundI )
    match HA' with 
    | [] -> Aout
    | r ->
        let (a, i) = r |> List.find(fun (_, i ) -> i |> Set.count = 1)
        let foundI' = foundI + i
        let Aout' = Aout |> Map.add a i
        let HA'' = HA' |> List.filter(snd >> fun s -> s <> i)
        find foundI' HA'' Aout'
let r = find Set.empty hasAllergenes2 Map.empty
let part2 = System.String.Join(",", r |> Map.toList |> List.map (snd >> fun s -> (Set.toList s |> List.head)))
printfn "part2: %s" part2