CPHInstance.java

package cph.instance;

import java.io.BufferedReader;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import java.util.StringTokenizer;

import jmh.instance.FormatException;
import jmh.instance.Instance;

/**
 * A Capacitated p-hub instance: nodes with (x, y) coordinates and a demand, a
 * number of hubs to open and the capacity of each hub.
 *
 * <p>Extends the generic {@link Instance} with the problem-specific data,
 * accessors, description and file parser. Node indices are 0-based, matching
 * the framework's default index mapping.
 */
public class CPHInstance extends Instance<CPHNode> {

    private final int numHubs;
    private final int hubCapacity;
    private final int[][] nodeData;

    public CPHInstance(String name, int numNodes, int numHubs, int hubCapacity, int[][] nodeData) {
        super(name);
        this.numHubs = numHubs;
        this.hubCapacity = hubCapacity;
        this.nodeData = nodeData;

        List<CPHNode> nodes = new ArrayList<>();
        for (int i = 0; i < numNodes; i++) {
            nodes.add(new CPHNode(i, this));
        }
        setNodes(nodes);
    }

    public int getX(int index) {
        return nodeData[index][0];
    }

    public int getY(int index) {
        return nodeData[index][1];
    }

    public int getDemand(int index) {
        return nodeData[index][2];
    }

    public int getNumHubs() {
        return numHubs;
    }

    public int getHubCapacity() {
        return hubCapacity;
    }

    @Override
    public String getDescription() {
        return getName() + " (n=" + getNumNodes() + ", p=" + numHubs + ", c=" + hubCapacity + ")";
    }

    /** Reads the CPH file format: header {@code numNodes numHubs hubCapacity}, then {@code node x y demand} lines. */
    public static CPHInstance parse(String name, BufferedReader br) throws IOException, FormatException {
        String line = br.readLine();
        if (line == null) {
            throw new FormatException("The file is empty");
        }

        StringTokenizer header = new StringTokenizer(line);
        int numNodes = Integer.parseInt(header.nextToken());
        if (header.countTokens() < 2) {
            throw new FormatException("The first line must contain the number of nodes, "
                    + "the number of hubs and the capacity of each hub");
        }
        int numHubs = Integer.parseInt(header.nextToken());
        int hubCapacity = Integer.parseInt(header.nextToken());

        int[][] nodeData = new int[numNodes][3];

        line = br.readLine();
        while (line != null && !line.isBlank()) {
            StringTokenizer st = new StringTokenizer(line);
            int node = Integer.parseInt(st.nextToken());
            int x = Integer.parseInt(st.nextToken());
            int y = Integer.parseInt(st.nextToken());
            int demand = Integer.parseInt(st.nextToken());

            nodeData[node][0] = x;
            nodeData[node][1] = y;
            nodeData[node][2] = demand;
            line = br.readLine();
        }

        return new CPHInstance(name, numNodes, numHubs, hubCapacity, nodeData);
    }

}