title: How to compare that two or more List(Integer) are equal?
body: <p>I hava to compare two Or more Set like List'&lt;'Integer'>' l1,List l2,List l3 ...,But How to compare them ?</p>
  
  <p>In my view,first Collections.sort(list),then l1.euqals(l2),and so on...
  But it seems not the effective way,It cost about O(n^2), and that there are not Two List,It may be three or four or more...</p>
  
  <p>And Anthoer Way is useing extra enough max Array A init Zero,first A[l1.get(i)] fill with A number Not-Zero,then A[l2.get(i)] fill with Zero, at last,if the Array A still full with Zero ,the two list are equal. And it cost O(n),but the trouble thing is not only two List...</p>
  
  <p>Is there any fast and efficient way which only cost less on time?
  I hope I express my mind clear .Hope ans!</p>