Package org.ddolib.examples.pdp

Class PDPDdoMain

java.lang.Object

org.ddolib.examples.pdp.PDPDdoMain

public final class PDPDdoMain
extends Object

Single Vehicle Pick-up and Delivery Problem (PDP) with Ddo. Main class for solving the Pickup and Delivery Problem (PDP) using the Dynamic Decision Diagram Optimization (DDO) approach.

This class demonstrates how to build and execute a DDO-based solver for a randomly generated PDP instance. The PDP involves scheduling a set of pickup and delivery tasks while minimizing the overall cost or time, typically under precedence and capacity constraints.

Execution workflow:

• A random PDP instance is generated using PDPGenerator.genInstance(int, int, int, java.util.Random).
• The instance is encapsulated in a DdoModel, which specifies:
  • the PDPProblem definition,
  • the PDPRelax relaxation used to merge states in the decision diagram,
  • the PDPRanking heuristic to prioritize state exploration,
  • a PDPFastLowerBound estimator to guide pruning,
  • a SimpleFrontier structure with CutSetType.Frontier for node management,
  • a width control strategy via FixedWidth to limit the diagram size.
• The DDO solver is executed through Solvers.minimizeDdo(DdoModel, java.util.function.BiConsumer).
• Each valid solution found is displayed using SolutionPrinter.printSolution(SearchStatistics, int[]).
• Global search statistics are printed at the end of execution.

Usage example:

 // Run the DDO solver on a randomly generated PDP instance
 java PDPDdoMain

 // Example output:
 Solution: [0, 2, 5, 7, ...]
 SearchStatistics{status=OPTIMAL, nodes=..., time=...}
 

Notes:

• The PDP instance is generated with a fixed random seed (new Random(1)) to ensure reproducible results.
• DDO explores an approximation of the full search space by iteratively refining decision diagrams, offering a good trade-off between accuracy and performance.
• Caching is enabled (useCache() = true) to avoid redundant computations across iterations.

See Also:

• PDPProblem
• PDPRelax
• PDPRanking
• PDPFastLowerBound
• Solvers.minimizeDdo(DdoModel, java.util.function.BiConsumer)
• DdoModel
• FixedWidth
• SimpleFrontier
• CutSetType

Constructor Summary

Constructors

Constructor	Description
PDPDdoMain()

Method Summary

Modifier and Type	Method	Description
static void	main(String[] args)	Entry point for solving a randomly generated Pickup and Delivery Problem (PDP) instance using the Dynamic Decision Diagram Optimization (DDO) method.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Details

PDPDdoMain

public PDPDdoMain()

Method Details

main

public static void main(String[] args)
                 throws IOException

Entry point for solving a randomly generated Pickup and Delivery Problem (PDP) instance using the Dynamic Decision Diagram Optimization (DDO) method.

The instance is created with predefined parameters and solved using a DDO model that integrates relaxation, ranking, lower bounds, and frontier management heuristics.

Parameters:

args - optional command-line arguments (not used in this example)

Throws:

IOException - if an error occurs during instance generation