数据结构与算法(C#实现)系列---AVLTree（一）[3]

         }

         //------------------------------------------------------------------

         protected override object getemptyinstance(uint _degree)

         {    return new avltree(); }

         //------------------------------------------------------------------

         protected int balancefactor()

         {

              if (this.isempty() )

                   return 0;

              return ((avltree)this.left).height-((avltree)this.right).height;