AdventOfCode 2020, December 3

AdventOfCode2020.12.03.fsx

open System
open System.IO

let area = 
    File.ReadAllLines("input03.txt") 
    |> Array.filter (not << String.IsNullOrEmpty)
    |> Array.map Seq.toArray
    |> Array.map (fun line -> line |> Array.map (fun x -> if x = '#' then 1 else 0))

let rec go steps (area : (int array) array) current_pos count =
    let (x,y) = current_pos
    if y + 1 = area.Length then
        count
    else
        let x = x + (fst steps)
        let y = y + (snd steps)
        let row = area.[y]
        let count = count + row.[x % row.Length]
        go steps area (x,y) count

[
    (1,1)
    (3,1)
    (5,1)
    (7,1)
    (1,2)
]
|> List.map (fun steps -> go steps area (0,0) 0)
|> List.map int64
|> List.reduce (*)