\par
\section{Data Structure}
\label{section:Graph:dataStructure}
\par
The {\tt Graph} structure has nine fields.
\begin{itemize}
\item {\tt int type} : type of graph \qquad
% \begin{center}
\begin{tabular}{|c|c|c|} \hline
{\tt type} & vertices weighted? & edges weighted? \\ \hline
         0 &  no &  no \\
         1 & yes &  no \\
         2 &  no & yes \\
         3 & yes & yes \\ \hline
\end{tabular}
% \end{center}
\item {\tt int nvtx } : number of internal vertices 
\item {\tt int nvbnd } : number of boundary vertices 
\item {\tt int nedges } : number of edges 
\item {\tt int totvwght } : total vertex weight 
\item {\tt int totewght } : total edge weight 
\item {\tt IVL *adjIVL} : 
pointer to {\tt IVL} object to hold adjacency lists
\item {\tt int *vwghts} : pointer to a vertex to hold vertex weights 
non-{\tt NULL} if {\tt type \% 2 == 1} 
\item {\tt IVL *ewghtIVL} : pointer to {\tt IVL} object to hold 
      edge weight lists, non-{\tt NULL} if {\tt type / 2 == 1} 
\end{itemize}

