question: void add ( int p1 , int p2 ) { int i = ncon ; if ( p1 >= nvert || p2 >= nvert ) { return ; } if ( i >= maxcon ) { if ( con == null ) { maxcon = 100 ; con = new int [ maxcon ] ; } else { maxcon *= 2 ; int nv [ ] = new int [ maxcon ] ; System . arraycopy ( con , 0 , nv , 0 , con . length ) ; con = nv ; } } if ( p1 > p2 ) { int t = p1 ; p1 = p2 ; p2 = t ; } con [ i ] = ( p1 << 16 ) | p2 ; ncon = i + 1 ; }
target:  Add a line from vertex p1 to vertex p2 