com.slothpetrochemical.bridgeprob.BridgeProblemApp.java Source code

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Here is the source code for com.slothpetrochemical.bridgeprob.BridgeProblemApp.java

Source

/*
 * Copyright (c) 2013. Released under MIT license, see LICENSE.txt.
 */

package com.slothpetrochemical.bridgeprob;

import com.slothpetrochemical.spdijklib.api.ProblemStateTransition;
import com.slothpetrochemical.spdijklib.api.Searcher;
import com.slothpetrochemical.spdijklib.api.TransitionAndTotalCost;
import com.slothpetrochemical.spdijklib.pqueue.PriorityQueueSearcher;
import org.apache.commons.cli.*;

import java.util.Arrays;
import java.util.Collection;

/**
 * Simple demo CLI showing use of API for the flashlight/bridge problem
 *
 * http://en.wikipedia.org/wiki/Bridge_and_torch_problem
 *
 * To run, enter travel times as arguments on command line:
 * e.g.
 * com.slothpetrochemical.bridgeprob.BridgeProblemApp 1 2 5 10
 * or
 * com.slothpetrochemical.bridgeprob.BridgeProblemApp 1 2 5 8
 *
 */
public final class BridgeProblemApp {
    public static final Integer DEFAULT_MAX_ITER = 1000;

    private final BridgeProblemStateFactory problemStateFactory;
    private final Searcher<BridgeProblemSignature> searcher;

    public BridgeProblemApp(final Collection<Integer> crossingTimes) {
        this.problemStateFactory = new BridgeProblemStateFactory(crossingTimes);
        this.searcher = new PriorityQueueSearcher<BridgeProblemSignature>(
                this.problemStateFactory.getStartStateSignature(), this.problemStateFactory.getEndStateSignature(),
                this.problemStateFactory);
    }

    public void run() {
        this.searcher.execute(DEFAULT_MAX_ITER);
        Searcher.SearchStatus s = this.searcher.getStatus();
        if (!s.equals(Searcher.SearchStatus.SUCCESS)) {
            System.out.println("Search ended with status: " + s.name());
        } else {
            Collection<TransitionAndTotalCost<BridgeProblemSignature>> transitions = this.searcher
                    .getShortestPath();
            printSignature(transitions.iterator().next().getTransition().getSource(), 0.0f, 0.0f);
            for (TransitionAndTotalCost<BridgeProblemSignature> transitionAndTotalCost : transitions) {
                ProblemStateTransition<BridgeProblemSignature> transition = transitionAndTotalCost.getTransition();
                printSignature(transition.getTarget(), transition.getCost(), transitionAndTotalCost.getTotalCost());
            }
            System.out.print(String.format("Search took %d total steps", this.searcher.getStepsChecked()));
        }
    }

    private static void printSignature(final BridgeProblemSignature signature, final float cost,
            final float totalCost) {
        System.out.println(String.format("%s\t%.2f (%.2f)", signature.toString(), cost, totalCost));
    }

    public static void main(final String[] args) throws ParseException {
        Options commandLineOptions = createOptions();
        PosixParser clParser = new PosixParser();
        CommandLine cl = clParser.parse(commandLineOptions, args);

        if (cl.getArgs().length == 0 || cl.hasOption("h")) {
            new HelpFormatter().printHelp("crossing_times...", commandLineOptions);
        } else {
            String[] clArgs = cl.getArgs();
            Integer[] times = new Integer[clArgs.length];
            for (int i = 0; i < clArgs.length; ++i) {
                Integer intTime = Integer.parseInt(clArgs[i]);
                times[i] = intTime;
            }
            Arrays.sort(times);
            BridgeProblemApp app = new BridgeProblemApp(Arrays.asList(times));
            app.run();
        }
    }

    private static Options createOptions() {
        Options options = new Options();
        options.addOption("h", "help", false, "Print this usage message");
        return options;
    }
}