Advent of Code 2022 - Day 4

open System.IO
open System

type Input() =

    let parseRanges (line: string) : (int * int) * (int * int) =
        let ranges =
            line.Split ','
            |> Seq.map (fun x -> x.Split '-' |> (fun y -> (y[0] |> int, y[1] |> int)))
            |> Seq.sortBy (fun (x, _) -> x)
            |> Array.ofSeq

        ranges[0], ranges[1]

    let includes (r1: int * int, r2: int * int) : int =
        if fst r1 < fst r2 then
            if snd r1 >= snd r2 then 1 else 0
        else if fst r1 = fst r2 then
            1
        else
            0

    let overlap (r1: int * int, r2: int * int) : int =
        if fst r1 < fst r2 then
            if snd r1 >= fst r2 then 1 else 0
        else if fst r1 = fst r2 then
            1
        else
            0

    let computePart1 (line: string) : int = line |> parseRanges |> includes

    let computePart2 (line: string) : int = line |> parseRanges |> overlap

    member _.Compute(part: int) =
        use stream = new StreamReader "./input.txt"

        let mutable sum = 0
        let mutable endOfFile = false

        while (not endOfFile) do
            let line = stream.ReadLine()

            if (line = null) then endOfFile <- true
            else if (part = 1) then sum <- sum + computePart1 line
            else sum <- sum + computePart2 line

        sum

let input = Input()
let part = (Environment.GetCommandLineArgs()[1]) |> int

printfn "%d" (input.Compute(part))