advent of code day 3 part 2

3b.rb

lines = File.readlines("3.txt")

def dl(lines, m)
  12.times do |pos|
    rs = lines.map(&:chars).map { |s| s[pos] }.tally
              .sort_by { |k, v| [v * m, k.ord * m] }
    lines.select! { |l| l[pos] == rs[1][0] }
    break lines.first.to_i(2) if lines.size == 1
  end
end

p dl(lines.dup, 1) * dl(lines.dup, -1)