/*
 * import CDG-file (CDG ... CostDelayGraph)
 */
int InstanceHandler::readCDG( Graph& graph, const char* filename )
{
	ifstream file( filename );
	if( !file.good() )
	{
		cerr << "File error." << endl;
		return -1;
	}

	u_int n_nodes;
	int cost;
	int delay;

	// line 1: number of nodes
	if( file >> n_nodes )
		graph.setNumberOfNodes( n_nodes );
	else
		return -1;

	// line 2 - EOF: edges ("<cost> <delay>") of complete graph
	for( u_int i = 0; i < n_nodes; i++ )
	{
		for( u_int j = i + 1; j < n_nodes; j++ )
		{
			if( file >> cost >> delay )
				graph.addEdge( i, j, cost, delay );
			else
				return -1;
		}
	}

	file.close();

	// the root node is always set to 0
	graph.setRootNode( 0 );	

	return 0;
}