aoc2022/bin/d2/main.ml

type choice
    = Rock
    | Paper
    | Scissors

let int_of_choice = function
    | Rock -> 1
    | Paper -> 2
    | Scissors -> 3

let choice_of_string = function
    | "A" | "X" -> Rock
    | "B" | "Y" -> Paper
    | "C" | "Z" -> Scissors
    |        _  -> failwith "invalid choice" ;;

type outcome
    = Draw
    | Win
    | Lose

let int_of_outcome = function
    | Lose -> 0
    | Draw -> 3
    | Win -> 6

let outcome_of_string = function
    | "X" -> Lose
    | "Y" -> Draw
    | "Z" -> Win
    |  _  -> failwith "invalid choice"

let choice_of_outcome oponent = function
    | Win -> if oponent = Rock then Paper else if oponent = Paper then Scissors else Rock
    | Lose -> if oponent = Rock then Scissors else if oponent = Paper then Rock else Paper
    | Draw -> if oponent = Rock then Rock else if oponent = Paper then Paper else Scissors

let outcome me oponent =
    match int_of_choice me - int_of_choice oponent with
    | -1 |  2 -> Lose
    |  1 | -2 -> Win
    |       _ -> Draw

open Utils

let solve f l = l
    |> List.map (fun line -> line
                    |> String.split_on_char ' '
                    |> pair_of_list
                    |> f
                    |> (fun (oponent, me) -> ((outcome me oponent) |> int_of_outcome) + int_of_choice me))
    |> List.fold_left (+) 0

let d2_1 = solve (fun (oponent_s, me_s) ->
    (choice_of_string oponent_s, choice_of_string me_s))

let d2_2 = solve (fun (oponent_s, outcome_s) ->
    (choice_of_string oponent_s, outcome_of_string outcome_s)
    |> (fun (oponent, outcome) -> (oponent, (choice_of_outcome oponent outcome))))

let _ = "\n1: " ^ (string_of_int (read_file "bin/d2/input.txt" |> d2_1)) ^
        "\n2: " ^ (string_of_int (read_file "bin/d2/input.txt" |> d2_2)) |> print_endline