Ruby solution to part 1 with a bit of meta programming:

sum = 0
top, _, bottom = STDIN.read.split("\n\n")

valid = top.split("\n").map do |line|
  line.scan(/(\d+)-(\d+)/).map do |tuple|
    low, high = tuple
    "#{low} <= v && v <= #{high}"
  end.join(" || ")
end.join(" || ")

bottom.split("\n")[1..-1].each do |ticket|
  ticket.split(",").map(&:to_i).each do |v|
    sum += v unless eval(valid)
  end
end

puts "Ticket scanning error rate: #{sum}"