Advent of Code 2023 - Day 2

README.md

@@ -1,3 +1,5 @@
+<a href="https://www.ruby-lang.org"><img src="https://s3.cdalvaro.io/github.com/cdalvaro/advent-of-code-2023/RubyLang.png" alt="Ruby" width="64px" margin="5px" align="right"/></a>
+
 # Advent of Code 2023
 
 This repo contains my solutions to the [Advent of Code 2023](https://adventofcode.com/2023) challenges, written in the [Ruby](https://www.ruby-lang.org) programming language.
@@ -18,10 +20,10 @@ bundle exec rake test
 
 ## Puzzles
 
-<a href="https://www.ruby-lang.org"><img src="https://s3.cdalvaro.io/github.com/cdalvaro/advent-of-code-2023/RubyLang.png" alt="Ruby" width="86px" margin="5px" align="right"/></a>
-
-|                 Day |                    Solution                     | Rank  |
-|--------------------:|:-----------------------------------------------:|:-----:|
-| [**1**][day01_link] | [`lib/puzzles/day01.rb`](lib/puzzles/day01.rb)  | ⭐🌟✴️ |
+|               Day |                    Solution                    | Rank  |
+|------------------:|:----------------------------------------------:|:-----:|
+| [1️⃣][day01_link] | [`lib/puzzles/day01.rb`](lib/puzzles/day01.rb) | ⭐🌟✴️ |
+| [2️⃣][day02_link] | [`lib/puzzles/day02.rb`](lib/puzzles/day02.rb) | ⭐🌟✴️ |
 
 [day01_link]: https://adventofcode.com/2023/day/1
+[day02_link]: https://adventofcode.com/2023/day/2

lib/puzzles/day01.rb

@@ -8,17 +8,20 @@ module Puzzles
     module Day01
       ##
       # Class for solving Day 01 - Part 1 puzzle
-      #
-      # On each line, the calibration value can be found by combining
-      # the first digit and the last digit (in that order) to form a
-      # single two-digit number.
       class Part1
         attr_reader :file_contents
 
+        ##
+        # @param file [String] file with puzzle input
         def initialize(file:)
           @file_contents = File.readlines(file, chomp: true)
         end
 
+        ##
+        # Compute the answer for the puzzle.
+        # The answer is the sum of all calibration values.
+        #
+        # @return [Integer] answer for the puzzle
         def answer
           calibration_values.sum
         end
@@ -68,10 +71,6 @@ def find_last_number(line)
 
       ##
       # Class for solving Day 01 - Part 2 puzzle
-      #
-      # It looks like some of the digits are actually spelled out with
-      # letters: one, two, three, four, five, six, seven, eight, and
-      # nine also count as valid "digits".
       class Part2 < Part1
         protected
 

lib/puzzles/day02.rb

@@ -0,0 +1,192 @@
+# frozen_string_literal: true
+
+module AdventOfCode
+  module Puzzles
+    ##
+    # Advent of Code 2023 - Day 2
+    # https://adventofcode.com/2023/day/2
+    module Day02
+      ##
+      # Set class to store the number of blue, green, and red cubes.
+      class Set
+        attr_reader :blue, :green, :red
+
+        ##
+        # @param blue [Integer] number of blue cubes
+        # @param green [Integer] number of green cubes
+        # @param red [Integer] number of red cubes
+        def initialize(blue: 0, green: 0, red: 0)
+          @blue = blue
+          @green = green
+          @red = red
+        end
+
+        ##
+        # Compute the power of the set by multiplying the number of
+        # blue, green, and red cubes.
+        #
+        # @return [Integer] power of the set
+        def power
+          return @power if @power
+
+          @power = (blue || 1) * (green || 1) * (red || 1)
+        end
+      end
+
+      ##
+      # Game class to store the game id and its sets.
+      class Game
+        attr_reader :id, :sets
+
+        ##
+        # @param id [Integer] game id
+        # @param sets [Array<Set>] sets of cubes
+        def initialize(id:, sets:)
+          @id = id
+          @sets = sets
+        end
+
+        ##
+        # Check if the game is valid given the number of blue, green,
+        # and red cubes.
+        #
+        # @param blue [Integer] number of blue cubes
+        # @param green [Integer] number of green cubes
+        # @param red [Integer] number of red cubes
+        #
+        # @return [Boolean] true if the game is valid, false otherwise
+        def valid?(blue:, green:, red:)
+          # A game is valid only if every set has the same or less
+          # number of blue, green, and red cubes as the set it is
+          sets.each do |set|
+            return false if set.blue > blue
+            return false if set.green > green
+            return false if set.red > red
+          end
+          true
+        end
+      end
+
+      ##
+      # Class for solving Day 02 - Part 1 puzzle
+      class Part1
+        attr_reader :games
+
+        ##
+        # @param file [String] path to the input file
+        def initialize(file:)
+          file_contents = File.readlines(file, chomp: true)
+          load_games(file_contents)
+        end
+
+        ##
+        # Find games that are valid given the number of blue, green,
+        # and red cubes.
+        #
+        # @param blue [Integer] number of blue cubes
+        # @param green [Integer] number of green cubes
+        # @param red [Integer] number of red cubes
+        #
+        # @return [Array<Game>] valid games
+        def valid_games(blue:, green:, red:)
+          games.select { |game| game.valid?(blue:, green:, red:) }
+        end
+
+        ##
+        # Find the sum of the game ids that are valid given the number
+        # of blue, green, and red cubes.
+        #
+        # @param blue [Integer] number of blue cubes
+        # @param green [Integer] number of green cubes
+        # @param red [Integer] number of red cubes
+        #
+        # @return [Integer] sum of the game ids
+        def answer(blue:, green:, red:)
+          valid_games(blue:, green:, red:).map(&:id).sum
+        end
+
+        protected
+
+        ##
+        # Load games from the file contents.
+        #
+        # @param file_contents [Array<String>] file contents
+        #
+        # @return [Array<Game>] games
+        def load_games(file_contents)
+          @games = file_contents.map do |line|
+            id, sets = line.split(": ")
+            sets = sets.split(%r{;\s+}).map { |set| parse_set(set) }
+            game_id = parse_game_id(id)
+            Game.new(id: game_id, sets:)
+          end
+        end
+
+        ##
+        # Parse the game id from a string.
+        # The string is in the format "Game X".
+        #
+        # @param game [String] game id
+        #
+        # @return [Integer] game id
+        def parse_game_id(game)
+          game.gsub("Game ", "").to_i
+        end
+
+        ##
+        # Parse a set of cubes from a string.
+        # The string is in the format "X blue, Y green, Z red".
+        #
+        # @param set [String] set of cubes
+        #
+        # @return [Set] set of cubes
+        def parse_set(set)
+          colors = set.split(%r{,\s+}).map(&:split)
+          colors = colors.to_h { |number, color| [color.downcase.to_sym, number.to_i] }
+          Set.new(**colors)
+        end
+      end
+
+      ##
+      # Class for solving Day 02 - Part 2 puzzle
+      class Part2 < Part1
+        ##
+        # Find the sum of the powers for the minimum valid sets.
+        #
+        # @return [Integer] sum of the powers
+        def answer
+          minimum_valid_sets.values.map(&:power).sum
+        end
+
+        ##
+        # Find the minimum valid set for each game.
+        #
+        # @return [Hash<Game, Set>] minimum valid sets
+        def minimum_valid_sets
+          @minimum_valid_sets ||= games.to_h { |game| [game, minimum_valid_set_for(game:)] }
+        end
+
+        protected
+
+        ##
+        # Find the minimum valid set for a game.
+        # The minimum valid set is the set with the maximum number of
+        # blue, green, and red cubes for all sets.
+        #
+        # @param game [Game] game to find the minimum valid set for
+        #
+        # @return [Set] minimum valid set
+        def minimum_valid_set_for(game:)
+          # Find the maximum number of blue, green, and red cubes in each set
+          minimum_set = { blue: 0, green: 0, red: 0 }
+          game.sets.each do |set|
+            %i[blue green red].each do |color|
+              minimum_set[color] = [set.send(color), minimum_set[color]].max
+            end
+          end
+          Set.new(**minimum_set)
+        end
+      end
+    end
+  end
+end

sig/puzzles/day01.rbs

@@ -1,37 +1,35 @@
 module AdventOfCode
-module Puzzles
-module Day01
+  module Puzzles
+    module Day01
 
-  class Part1
+      class Part1
 
-    @calibration_values: [Integer]
+        @calibration_values: [Integer]
 
-    @file_contents: [String]
+        attr_reader file_contents: [String]
 
-    def answer: () -> Integer
+        def answer: () -> Integer
 
-    def calibration_values: () -> [Integer]
+        def calibration_values: () -> [Integer]
 
-    def file_contents: () -> [String]
+        def find_first_number: () -> Integer?
 
-    def find_first_number: () -> Integer?
+        def find_last_number: () -> Integer?
 
-    def find_last_number: () -> Integer?
+        def select_number: (String) -> Integer
+      end
 
-    def select_number: (String) -> Integer
-  end
-
-  class Part2
+      class Part2
 
-    TRANSLATIONS: { String: Integer }
+        TRANSLATIONS: { String: Integer }
 
-    def find_first_number: (String) -> Integer
+        def find_first_number: (String) -> Integer
 
-    def find_last_number: (String) -> Integer
+        def find_last_number: (String) -> Integer
 
-    def translate_contents: () -> void
+        def translate_contents: () -> void
 
+      end
+    end
   end
 end
-end
-end

sig/puzzles/day02.rbs

@@ -0,0 +1,52 @@
+module AdventOfCode
+  module Puzzles
+    module Day02
+
+      class Set
+
+        @power: Integer
+
+        attr_reader blue: Integer
+        attr_reader green: Integer
+        attr_reader red: Integer
+
+        def power: () -> Integer
+      end
+
+      class Game
+
+        attr_reader id: Integer
+        attr_reader sets: [Set]
+
+        def valid?: (Integer, Integer, Integer) -> bool
+      end
+
+      class Part1
+
+        attr_reader games: [Game]
+
+        def answer: (Integer, Integer, Integer) -> Integer
+
+        def load_games: ([String]) -> [Game]
+
+        def parse_game_id: (String) -> Integer
+
+        def parse_set: (String) -> Set
+
+        def valid_games: (Integer, Integer, Integer) -> [Game]
+      end
+
+      class Part2
+
+        @minimum_valid_sets: {Game: Set}
+
+        def answer: () -> Integer
+
+        def minimum_valid_sets: () -> {Game: Set}
+
+        def minimum_valid_set_for: (Game) -> Set
+      end
+
+    end
+  end
+end

sig/test/puzzles/day02_test.rbs

@@ -0,0 +1,27 @@
+module Puzzles
+  module Day02
+    class Part1Test
+      def setup: -> untyped
+
+      def teardown: -> untyped
+
+      def test_answer_input_set: -> untyped
+
+      def test_answer_test_data_set: -> untyped
+
+      def test_valid_games_test_data_set: -> untyped
+    end
+
+    class Part2Test
+      def setup: -> untyped
+
+      def teardown: -> untyped
+
+      def test_answer_input_set: -> untyped
+
+      def test_answer_test_data_set: -> untyped
+
+      def test_valid_games_test_data_set: -> untyped
+    end
+  end
+end