Package edu.cnu.mdi.sim.simanneal.tspdemo

Class TspMove

java.lang.Object

edu.cnu.mdi.sim.simanneal.tspdemo.TspMove

All Implemented Interfaces:

AnnealingMove<TspSolution>, DeltaEnergyMove<TspSolution>, ReversibleAnnealingMove<TspSolution>

public class TspMove
extends Object
implements DeltaEnergyMove<TspSolution>

A 2-opt move for TSP that supports O(1) ΔE computation.

The move reverses a contiguous segment [i..k] in-place. It is parameterized by the endpoints i < k chosen in prepare(TspSolution). The same prepared parameters are used by deltaE(TspSolution) and apply(TspSolution).

Undo is performed by reversing the same segment again.

Constructor Summary

Constructors

Constructor	Description
TspMove(Random rng)	Create a reusable random 2-opt move.

Method Summary

Modifier and Type	Method	Description
void	apply(TspSolution sol)	Apply the prepared 2-opt reversal in-place.
double	deltaE(TspSolution sol)	Compute the exact ΔE for the prepared 2-opt reversal.
void	prepare(TspSolution sol)	Choose a non-degenerate 2-opt segment for the next move.
void	undo(TspSolution sol)	Undo by reversing the same segment again.

Methods inherited from class java.lang.Object

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

Constructor Details

TspMove

public TspMove(Random rng)

Create a reusable random 2-opt move.

Parameters:

rng - source of randomness

Method Details

prepare

public void prepare(TspSolution sol)

Choose a non-degenerate 2-opt segment for the next move.

Specified by:

prepare in interface DeltaEnergyMove<TspSolution>

Parameters:

sol - current solution (non-null)

Throws:

IllegalArgumentException - if the solution or tour is null, or the tour contains fewer than four cities

deltaE

public double deltaE(TspSolution sol)

Compute the exact ΔE for the prepared 2-opt reversal.

Specified by:

deltaE in interface DeltaEnergyMove<TspSolution>

Parameters:

sol - current solution (non-null)

Returns:

ΔE = E_after - E_before for the prepared segment

Throws:

IllegalStateException - if called before prepare(edu.cnu.mdi.sim.simanneal.tspdemo.TspSolution)

apply

public void apply(TspSolution sol)

Apply the prepared 2-opt reversal in-place.

Specified by:

apply in interface ReversibleAnnealingMove<TspSolution>

Parameters:

sol - current solution (non-null)

Throws:

IllegalStateException - if called before prepare(edu.cnu.mdi.sim.simanneal.tspdemo.TspSolution)

undo

public void undo(TspSolution sol)

Undo by reversing the same segment again.

Specified by:

undo in interface ReversibleAnnealingMove<TspSolution>

Parameters:

sol - current solution (non-null)