Day 2 solution

examples/02.txt

@@ -0,0 +1,5 @@
+Game 1: 3 blue, 4 red; 1 red, 2 green, 6 blue; 2 green
+Game 2: 1 blue, 2 green; 3 green, 4 blue, 1 red; 1 green, 1 blue
+Game 3: 8 green, 6 blue, 20 red; 5 blue, 4 red, 13 green; 5 green, 1 red
+Game 4: 1 green, 3 red, 6 blue; 3 green, 6 red; 3 green, 15 blue, 14 red
+Game 5: 6 red, 1 blue, 3 green; 2 blue, 1 red, 2 green

lib/days/02.rb

@@ -0,0 +1,43 @@
+class Day02
+
+  Game = Struct.new(:id, :red, :green, :blue) do
+    def possible?(red:, green:, blue:)
+      self.red <= red && self.green <= green && self.blue <= blue
+    end
+
+    def power
+      red * green * blue
+    end
+  end
+
+  def build_games_from_input(input)
+    input.split("\n").each_with_index.map do |line, index|
+      game = Game.new(index + 1, 0, 0, 0)
+
+      line.split(': ').last.split('; ').each do |set|
+        set.split(', ').each do |hand|
+          number, color = hand.split
+          case color
+          when 'red'
+            game.red = [game.red, number.to_i].max
+          when 'green'
+            game.green = [game.green, number.to_i].max
+          when 'blue'
+            game.blue = [game.blue, number.to_i].max
+          end
+        end
+      end
+
+      game
+    end
+  end
+
+  def part1(input)
+    build_games_from_input(input).select { |g| g.possible?(red: 12, green: 13, blue: 14) }.sum(&:id)
+  end
+
+  def part2(input)
+    build_games_from_input(input).sum(&:power)
+  end
+
+end

test/02_test.rb

@@ -0,0 +1,18 @@
+require 'minitest/autorun'
+require 'minitest/pride'
+require_relative '../app'
+
+class TestDay02 < Minitest::Test
+  def setup
+    @data = File.read(File.join(APP_ROOT, 'examples', '02.txt')).rstrip
+    @day = Day02.new
+  end
+
+  def test_part1
+    assert_equal @day.part1(@data), 8
+  end
+
+  def test_part2
+    assert_equal @day.part2(@data), 2286
+  end
+end