//Torbert, 11.12.2003
   import java.util.ArrayList;
   public class Permute
   {
      public static void main(String[] args)
      {
         ArrayList list = new ArrayList();
         String s = "AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA";
         permute(s, "", list, s.length());
         System.out.println(list);
      
         // empty(list);
         // System.out.println();
      // 
         // permute("AACD", "", list, 2);
         // System.out.println(list);
      }
      public static void empty(ArrayList al)
      {
         while(!al.isEmpty())
            al.remove(al.size() - 1);
      
      	//Do not use remove(0), shifts left	= O(n) = bad.
      	//If this was a LinkedList, though, the thinking
      	//is reversed and you DO use remove(0) = O(1).
      }
      public static void permute(String s, String t, ArrayList al, int n)
      {
         if(t.length() == n)
            al.add(t);
         else
         {
            String r = "";
            for(int k = 0; k < s.length(); k++)
            {
               if(r.indexOf(s.charAt(k)) == -1)
               {
                  permute(s.substring(0, k) + s.substring(k + 1),
                     t + s.charAt(k), al, n);
                  r = r + s.charAt(k);
               }
            }
         }
      }
   }