Program.fs

module Day02

open System.IO

let partOne row = Array.max row - Array.min row

let divides =
    function
    | (a, b) when a % b = 0 -> Some(a / b)
    | (a, b) when b % a = 0 -> Some(b / a)
    | _ -> None

let partTwo row =
    Array.allPairs row row
    |> Array.filter (fun (a, b) -> a <> b)
    |> Array.pick divides

[<EntryPoint>]
let main argv =
    let input = File.ReadAllLines("input.txt") |> Seq.map ((fun row -> row.Split("\t")) >> Array.map int)

    input |> Seq.sumBy partOne |> printfn "Part one: %d"
    input |> Seq.sumBy partTwo |> printfn "Part two: %d"

    0 // return an integer exit code