Stores the Tree
@ SuppressWarnings ( " unchecked " ) Vector < Integer > [ ] tr = new Vector [ n + 1 ] ; for ( int i = 0 ; i < tr . length ; i ++ ) tr [ i ] = new Vector < Integer > ( ) ; tr [ 0 ] . add ( 3 ) ; tr [ 0 ] . add ( 4 ) ; tr [ 4 ] . add ( 6 ) ; tr [ 6 ] . add ( 2 ) ; tr [ 2 ] . add ( 1 ) ; tr [ 2 ] . add ( 8 ) ; tr [ 8 ] . add ( 5 ) ; tr [ 5 ] . add ( 7 ) ;