public class LongestWalkProcessor<Data> extends EmptyProcessor<Data, int[]> { 
    /*
     * Forge (1)
     */
        LongestWalkProcessor(); 
    /*
     * Type (3)
     */
        void before(Graph<Data> g); 
        void after(Vertex<Data> v); 
        int[] after(Graph<Data> _); 
} 

// SSDLPedia
package il.ac.technion.cs.cs236700.graph;

import static java.lang.Math.max;
import il.ac.technion.cs.cs236700.graph.Graph.Vertex;

/**
 * Computes the longest walk from every node. Assumes that the graph has no
 * cycles, otherwise, the traversal will terminate but the result may not make
 * sense to some.
 * 
 * <Data> the type of information stored in a graph node
 * Author: Yossi Gil 
 * See:  26/06/2007
 */
public class LongestWalkProcessor<Data extends Comparable<Data>> extends EmptyProcessor<Data, int[]> {
    /**
     * Result of the longest walk computation. Position i in this
     * array will store the length of the longest walk possible starting from
     * the vertex numbered i.
     */
    private int[] result;
    
    @Override public void before(final Graph<Data> g) {
        result = new int[g.vertices.length];
    }
    
    @Override public void after(final Vertex<Data> v) {
        for (final Vertex<Data> u : v.to)
            if (u != v)
                result[v.i] = max(result[v.i], 1 + result[u.i]);
    }
    
    @Override public int[] after(@SuppressWarnings("unused") final Graph<Data> _) {
        return result;
    }
}