From: brabuhr@...
Date: 2009-11-24T07:25:57+09:00
Subject: Re: Distinct Sets (#225)

Here's my not-fast solution:

require 'set'

class Set
  def intersect?(other)
    other.each { |o| return true if include?(o) }
    false
  end
end

def distinct_sets(array_of_arrays)
  set_of_sets = array_of_arrays.map{|a|
    a.to_set
  }.to_set

  set_of_sets.divide{|i, j|
    i.intersect?(j)
  }.map{|s|
    s.flatten.to_a
  }
end

Adding the intersect? method to Set was primarily motivated by
readability, but also provided a noticeable speed improvement over my
original alternative (intersection.size.>).