match_urls_in_cities.rb

def match_urls_in_cities(file_names)
  cities_count = {}
  file_names.each do |file_name|
    File.open(file_name, "r") do |f|
      f.each_line do |line|
        city_name = line.match(/(.*)\t/)[0].gsub("\t", "")
        cities_count[city_name] ||= 0
        cities_count[city_name] += 1 if is_url_present?(line)
      end
    end
  end
  p cities_count
end

private
def is_url_present?(line)
  line.match(/(http[s]?\:\/\/)[a-z0-9._]+/).tap do |matched_val|
    return true if matched_val
  end
  return false
end

match_urls_in_cities(["tweets_aa", "tweets_ab", "tweets_ac"])