swingers.rb

def swingers(couples)
  randomized_couples = couples.shuffle
  randomized_couples.each_with_index do |couple, index|
    if index != randomized_couples.length - 1
      randomized_couples[index][1], randomized_couples[index+1][1] = randomized_couples[index+1][1], randomized_couples[index][1]
    end
  end
end