Array Permutation

hardcoded.rb

def self.permute(one, two, three)
  result = []
  one.each do |x|
    two.each do |y|
      three.each do |z|
        result << [x, y, z]
      end
    end
  end
  result
end

recursive.rb

def self.permute(arrays, results=[], current=[])
  arrays[0].each do |item|
    if arrays[1..-1].empty?
      results << current + [item]
    else
      permute(arrays[1..-1], results, current + [item])
    end
  end
  results
end

Generalize for (n) arrays.