day_02.ex

defmodule AdventOfCode.Day02 do

  @loss 0
  @draw 3
  @win 6

  @rock 1
  @paper 2
  @scisors 3

  def part1(input) do
    input
    |> Enum.map(&String.split/1)
    |> Enum.map(&rps/1)
    |> Enum.sum
  end

  def part2(input) do
    input
    |> Enum.map(&String.split/1)
    |> Enum.map(&rpr/1)
    |> Enum.sum
  end


  def rps(["A", "X"]), do: @rock + @draw
  def rps(["B", "X"]), do: @rock + @loss
  def rps(["C", "X"]), do: @rock + @win

  def rps(["A", "Y"]), do: @paper + @win
  def rps(["B", "Y"]), do: @paper + @draw
  def rps(["C", "Y"]), do: @paper + @loss

  def rps(["A", "Z"]), do: @scisors + @loss
  def rps(["B", "Z"]), do: @scisors + @win
  def rps(["C", "Z"]), do: @scisors + @draw

  def rps([]), do: 0

  def rpr(["A", "X"]), do: @scisors + @loss
  def rpr(["B", "X"]), do: @rock + @loss
  def rpr(["C", "X"]), do: @paper + @loss

  def rpr(["A", "Y"]), do: @rock + @draw
  def rpr(["B", "Y"]), do: @paper + @draw
  def rpr(["C", "Y"]), do: @scisors + @draw

  def rpr(["A", "Z"]), do: @paper + @win
  def rpr(["B", "Z"]), do: @scisors + @win
  def rpr(["C", "Z"]), do: @rock + @win

  def rpr([]), do: 0
end