LexTreeSearchGraph API

<span style="font-size:24px;"> class LexTreeSearchGraph implements SearchGraph
   lextree    。
     ：
  /** An array of classes that represents the order in which the states will be returned. */
 private SearchState initialState;    。
    ：
 LexTreeSearchGraph(SearchState initialState)；               。
     ：
   public SearchState getInitialState()；      。
  public int getNumStateOrder() ；    6</span>