Day 2 - Rock Paper Scissors

Mix.install([{:kino, "~> 0.7.0"}])

:ok

Part 1

input = Kino.Input.textarea("Please insert your input")

A for Rock, B for Paper, and C for Scissors. X for Rock, Y for Paper, and Z for Scissors.

The score for a single round is the score for the shape you selected (1 for Rock, 2 for Paper, and 3 for Scissors) plus the score for the outcome of the round (0 if you lost, 3 if the round was a draw, and 6 if you won)

sample_input =
  input
  |> Kino.Input.read()
  |> String.split("\n", trim: true)

scores_map = %{
  # opponent: rocks, you: rocks => draw
  "A X" => 1 + 3,
  # opponent: rocks, you: paper => win
  "A Y" => 2 + 6,
  # opponent: rocks, you: scissors => loss
  "A Z" => 3 + 0,
  # opponent: paper, you: rocks => loss
  "B X" => 1 + 0,
  # opponent: paper, you: paper => draw
  "B Y" => 2 + 3,
  # opponent: paper, you: scissors => win
  "B Z" => 3 + 6,
  # opponent: scissors, you: rock => win
  "C X" => 1 + 6,
  # opponent: scissors, you: paper => loss
  "C Y" => 2 + 0,
  # opponent: scissors, you: rock => draw
  "C Z" => 3 + 3
}

%{
  "A X" => 4,
  "A Y" => 8,
  "A Z" => 3,
  "B X" => 1,
  "B Y" => 5,
  "B Z" => 9,
  "C X" => 7,
  "C Y" => 2,
  "C Z" => 6
}

sample_input
|> Enum.map(fn play ->
  Map.get(scores_map, play)
end)
|> Enum.sum()

11449

Part 2

X means you need to lose, Y means you need to end the round in a draw, and Z means you need to win.

new_scores_map = %{
  # opponent: rocks, you: scissors => loss
  "A X" => 3 + 0,
  # opponent: paper, you: rocks => loss
  "B X" => 1 + 0,
  # opponent: scissors, you: paper => loss
  "C X" => 2 + 0,
  # opponent: rocks, you: rocks => draw
  "A Y" => 1 + 3,
  # opponent: paper, you: paper => draw
  "B Y" => 2 + 3,
  # opponent: scissors, you: scissors => draw
  "C Y" => 3 + 3,
  # opponent: rocks, you: paper => win
  "A Z" => 2 + 6,
  # opponent: paper, you: scissors => win
  "B Z" => 3 + 6,
  # opponent: scissors, you: rock => win
  "C Z" => 1 + 6
}

%{
  "A X" => 3,
  "A Y" => 4,
  "A Z" => 8,
  "B X" => 1,
  "B Y" => 5,
  "B Z" => 9,
  "C X" => 2,
  "C Y" => 6,
  "C Z" => 7
}

sample_input
|> Enum.map(fn play ->
  Map.get(new_scores_map, play)
end)
|> Enum.sum()

13187