merge-lists.rb

require "csv"

input = File.readlines(ARGV[0], chomp: true).map do |line|
    line.split(/,/)
end

unique_elements = input.flatten.uniq.size

def merge(input)
    data = input.clone
    candidate = data.shift
    @match = false
    data.each_with_index do |line, i|
        if (candidate & line).count > 0
            data[i] = (candidate + line).uniq.sort
            @match = true
            break
        end
    end
    if @match == false
        data << candidate
    end
    data
end

while true
    output = merge(input)
    if unique_elements == input.flatten.size
        break
    end
    input = output
end

CSV do |csv|
    output.each do |line|
        csv << line
    end
end