package graph;
import java.util.Vector;
import java.util.Enumeration;

/**
 * A class for storing adjacency information about a graph.
 * Each element <i>[i,j]</i> in the matrix represents an edge from 
 * node <i>i</i> to node <i>j</i>.
 *
 * <pre>
 *             A   B   C (head)
 *           +----------
 * (tail)  A | 1   2
 *         B | 2       1
 *         C |     3
 * </pre>
 *
 * @see Graph
 * @author Michael Shilman (michaels@eecs.berkeley.edu)
 * @version $Id$
 */
public class AdjacencyMatrix extends Matrix {
	/**
	 * The names of the nodes in the graph.
	 */
	public String[] names = null;
	
	/**
	 * The name of the graph.
	 */
	public String name = null;
	
	/**
	 * Whether or not the graph is directed.
	 */
	public boolean directed = false;
	
	/**
	 * Create a new matrix of fixed dimension with no 
	 * node names and no edges.
	 *
	 * @param w		The dimension of the matrix (number of nodes).
	 */
	public AdjacencyMatrix(int w) {
		super(w,w);
		names = new String[w];
	}

 	/**
     * Create a matrix which represents an existing Graph.
     * 
     * @param g		The Graph whose contents are being represented
     */
	public AdjacencyMatrix(Graph g) {
    	super(g.nodes.size(), g.nodes.size());
		names = new String[g.nodes.size()];
		name = g.name;
		int i = 0;
        for(Enumeration e = g.nodes.elements(); e.hasMoreElements(); ) {
            Node n = (Node)e.nextElement();
            names[i++] = n.name;
            for(int j = 0; j < n.out.size(); j++) {
            	Edge edge = (Edge)n.out.elementAt(j);
            	int x = g.nodes.indexOf(edge.head);
            	int y = g.nodes.indexOf(edge.tail);
            	values[x][y] = edge.weight;
            }
        }
	}

 	/**
     * Print out the graph in .ADJ format.
     */
	public String toString() {
		String s = new String();
		
		int w = values.length;
		int h = values[0].length;
		for(int i = 0; i < h; i++) {
			for(int j = 0; j < w; j++) {
				s = s + "\t" + values[i][j];
			}
			s = s + "\t" + names[i] + "\n";
		}
		return s;
	}
}