Advent of Code 2022 - Day 2

Day 2: Rock Paper Scissors

Description

Utils

defmodule Load do
  def file(path) do
    File.read!(__DIR__ <> path)
    |> String.split("\n", trim: true)
  end

  def string(value) do
    value |> String.split("\n", trim: true)
  end
end

Input

input = Load.file("/data/day02.txt")

Part 1

What would your total score be if everything goes exactly according to your strategy guide?

values = %{
  "A" => 1,
  "B" => 2,
  "C" => 3,
  "X" => 1,
  "Y" => 2,
  "Z" => 3
}

input
|> Enum.map(&String.split/1)
|> Enum.map(fn round ->
  [them, me] = round
  my_value = Map.get(values, me)
  their_value = Map.get(values, them)

  outcome =
    cond do
      their_value == my_value -> 3
      [them, me] == ["A", "Y"] -> 6
      [them, me] == ["B", "Z"] -> 6
      [them, me] == ["C", "X"] -> 6
      true -> 0
    end

  my_value + outcome
end)
|> Enum.sum()

Result

13009

Part 2

Following the Elf’s instructions for the second column, what would your total score be if everything goes exactly according to your strategy guide?

values = %{
  "A" => 1,
  "B" => 2,
  "C" => 3,
  # Score when I should lose
  "A_X" => 3,
  "B_X" => 1,
  "C_X" => 2,
  # Score when I should win
  "A_Z" => 2,
  "B_Z" => 3,
  "C_Z" => 1
}

input
|> Enum.map(&String.split/1)
|> Enum.map(fn round ->
  [them, outcome] = round

  case outcome do
    "X" -> 0 + Map.get(values, them <> "_X")
    "Y" -> 3 + Map.get(values, them)
    "Z" -> 6 + Map.get(values, them <> "_Z")
  end
end)
|> Enum.sum()

Result

10398