advend-of-code-2023-in-ruby/src/advent/day7.rb

# frozen_string_literal: true

module HandTypeName
  FIVE_OF_A_KIND = 7
  FOUR_OF_A_KIND = 6
  FULL_HOUSE = 5
  THREE_OF_A_KIND = 4
  TWO_PAIR = 3
  ONE_PAIR = 2
  HIGH_CARD = 1

end

class HandType
  def initialize(type_name, card_value)
    @type_name = type_name
    @card_value = card_value.split("").sort.join("")
  end

  def ==(o)
    o.class == self.class && o.type_name == @type_name && o.card_value == @card_value
  end

  def <=>(o)
    @type_name <=> o.type_name
  end

  attr_accessor :type_name
  attr_accessor :card_value
end


def compare_card(card1, card2)
  ordered_cards = "AKQJT98765432".reverse
  if !ordered_cards.include?(card1) || !ordered_cards.include?(card2)
    raise Exception.new("Unknown card #{card1} or #{card2}")
  end
  ordered_cards.index(card1) <=> ordered_cards.index(card2)
end

class Hand
  def initialize(cards, bid)
    @cards = cards
    @bid = bid
  end

  def _card_map
    card_map = {}
    @cards.each_char do |card|
      if card_map.include? card
        card_map[card] += 1
      else
        card_map[card] = 1
      end
    end
    card_map
  end

  def _reversed_card_map
    ret = {}
    _card_map.each_pair do |key, value|
      if ret.include? value
        ret[value].append key
      else
        ret[value] = [key]
      end
    end
    ret
  end

  def _get_five_of_a_kind
    if _card_map.values.include? 5
      return HandType.new HandTypeName::FIVE_OF_A_KIND, _reversed_card_map[5][0]
    end
    nil
  end

  def _get_four_of_a_kind
    if _card_map.values.include? 4
      return HandType.new HandTypeName::FOUR_OF_A_KIND, _reversed_card_map[4][0]
    end
    nil
  end

  def _get_full_house
    if _card_map.values.include?(3) && _card_map.values.include?(2)
      return HandType.new HandTypeName::FULL_HOUSE, _reversed_card_map[3][0] + _reversed_card_map[2][0]
    end
    nil
  end

  def _get_three_of_a_kind
    if _card_map.values.include?(3)
      return HandType.new HandTypeName::THREE_OF_A_KIND, _reversed_card_map[3][0]
    end
    nil
  end

  def _get_two_pairs
    if _card_map.values.include?(2) && (_reversed_card_map[2].length == 2)
      return HandType.new HandTypeName::TWO_PAIR, _reversed_card_map[2][0] +  _reversed_card_map[2][1]
    end
    nil
  end

  def _get_one_pair
    if _card_map.values.include?(2)
      return HandType.new HandTypeName::ONE_PAIR, _reversed_card_map[2][0]
    end
    nil
  end

  def _get_high_card
    high_card = @cards.split("").sort {|c1, c2| compare_card(c1, c2)} .last
    HandType.new HandTypeName::HIGH_CARD, high_card
  end

  def get_type
    (_get_five_of_a_kind or
     _get_four_of_a_kind or
     _get_full_house or
     _get_three_of_a_kind or
     _get_two_pairs or
     _get_one_pair or
      _get_high_card)
  end

  def <=>(other)
    if (get_type <=> other.get_type) != 0
      return get_type <=> other.get_type
    end
    ((0...5).map {|i| compare_card(@cards[i], other.cards[i])}.drop_while { |v| v == 0}.first) or 0
  end

  def self.deserialize(line)
    parts = line.split(/\s+/)
    self.new parts[0], parts[1].to_i

  end


  attr_accessor :cards
  attr_accessor :bid
end


def play_part_1_game(input)
  input.strip.split("\n")
       .filter {|line| !line.empty?}
       .map {|line| Hand.deserialize line}
       .sort
       .each_with_index
       .map {|hand, idx| hand.bid * (idx + 1)}
       .reduce 0, :+
end



if __FILE__ == $0
  input_file_name = File.join(File.dirname(__FILE__), "day_7_input.txt")
  input_content = File.open(input_file_name).read

  puts "Solution to part 1: #{play_part_1_game input_content}"

end