path: root/solutions/day2.fs

module Solutions.Day2
open System.IO

let lines = File.ReadLines("inputs/day2.txt") |> Seq.map (fun x -> x[0], x[2])

let outcomes1 = Map.empty
                    .Add(('A', 'X'), 4) // rock: 1 + tie: 3
                    .Add(('A', 'Y'), 8) // paper: 2 + rock win: 6
                    .Add(('A', 'Z'), 3) // scissors: 3 + rock lose: 0
                    .Add(('B', 'X'), 1) // rock: 1 + paper lose: 0
                    .Add(('B', 'Y'), 5) // paper: 2 + tie: 3
                    .Add(('B', 'Z'), 9) // scissors: 3 + paper win: 6
                    .Add(('C', 'X'), 7) // rock: 1 + scissors win: 6
                    .Add(('C', 'Y'), 2) // paper: 2 + scissors lose: 0
                    .Add(('C', 'Z'), 6) // scissors: 3 + tie: 3

let part1 () = lines |> Seq.map outcomes1.TryFind |> Seq.map (function | Some value -> value | None -> 0) |> Seq.sum

let outcomes2 = Map.empty
                    .Add(('A', 'X'), 3) // lose to rock: 0 pts + 3 for scissors
                    .Add(('A', 'Y'), 4) // draw to rock: 3 pts + 1 for rock
                    .Add(('A', 'Z'), 8) // win to rock: 6 pts + 2 for paper
                    .Add(('B', 'X'), 1) // lose to paper: 0 pts + 1 for rock
                    .Add(('B', 'Y'), 5) // draw to paper: 3 pts + 2 for paper
                    .Add(('B', 'Z'), 9) // win to paper: 6 pts + 3 for scissors
                    .Add(('C', 'X'), 2) // lose to scissors: 0 pts + 2 for paper
                    .Add(('C', 'Y'), 6) // draw to scissors: 3 pts + 3 for scissors
                    .Add(('C', 'Z'), 7) // win to scissors: 6 pts + 1 for rock

let part2 () = lines |> Seq.map outcomes2.TryFind |> Seq.map (function | Some value -> value | None -> 0) |> Seq.sum