AoC2022/day02/solution.rb

#!/bin/env ruby
# frozen_string_literal: true

require 'pry'

def score(opponent, me)
  base = case me
         when :rock
           1
         when :paper
           2
         when :scissors
           3
         end
  return 3 + base if opponent == me

  outcome = 0
  outcome = 6 if (opponent == :rock) && (me == :paper)
  outcome = 6 if (opponent == :paper) && (me == :scissors)
  outcome = 6 if (opponent == :scissors) && (me == :rock)

  outcome + base
end

input = File.readlines('./input').map(&:strip)

guide = input.map do |pair|
  pair.split.map do |letter|
    case letter
    when 'A', 'X'
      :rock
    when 'B', 'Y'
      :paper
    when 'C', 'Z'
      :scissors
    end
  end
end

scores = guide.map do |pair|
  score(pair[0], pair[1])
end

puts "Part 1 Solution: #{scores.sum}"

## Part 2
def wins_to?(throw)
  case throw
  when :rock
    :paper
  when :paper
    :scissors
  when :scissors
    :rock
  end
end

def loses_to?(throw)
  case throw
  when :rock
    :scissors
  when :paper
    :rock
  when :scissors
    :paper
  end
end

guide2 = input.map do |pair|
  pair.split.map do |letter|
    case letter
    when 'A'
      :rock
    when 'B'
      :paper
    when 'C'
      :scissors
    when 'X'
      :lose
    when 'Y'
      :draw
    when 'Z'
      :win
    end
  end
end

guide2.map! do |opponent, outcome|
  throw = case outcome
          when :draw
            opponent
          when :win
            wins_to?(opponent)
          when :lose
            loses_to?(opponent)
          end
  [opponent, throw]
end

scores2 = guide2.map do |pair|
  score(pair[0], pair[1])
end

puts "Part 2 Solution: #{scores2.sum}"