Advent of Code day 4

part1.rb

puts DATA.readlines.sum { |line|
  _, winning_numbers, my_numbers = line.split(/[:|]/).map(&:split)
  wins = (winning_numbers & my_numbers).length
  wins.zero? ? 0 : 2**(wins - 1)
}

__END__
Data goes here

part2.rb

lines = DATA.readlines

count_per_card = 1.upto(lines.length).to_h { [ _1, 1 ] }

lines.each.with_index(1) do |line, i|
  _, winning_numbers, my_numbers = line.split(/[:|]/).map(&:split)
  wins = (winning_numbers & my_numbers).length

  count_per_card[i].times do
    1.upto(wins) { count_per_card[i + _1] += 1 }
  end
end

puts count_per_card.values.sum

__END__
Data goes here