Package org.ddolib.examples.gruler

Class GRRanking

java.lang.Object

org.ddolib.examples.gruler.GRRanking

All Implemented Interfaces:

Comparator<GRState>, StateRanking<GRState>

public class GRRanking
extends Object
implements StateRanking<GRState>

Defines a ranking strategy for states in the Golomb Ruler (GR) problem.

This class provides a simple heuristic ordering between two GRState objects based on the position of their last mark. It can be used by search algorithms such as DDO, A*, or Anytime Column Search to prioritize exploration.

The comparison criterion is straightforward: the state with the smaller last mark (i.e., the shorter current ruler) is considered better.

Example usage:

 GRRanking ranking = new GRRanking();
 int result = ranking.compare(state1, state2);
 // result < 0 means state1 is preferred (smaller last mark)
 

See Also:

• GRState
• StateRanking

Constructor Summary

Constructors

Constructor	Description
GRRanking()

Method Summary

Modifier and Type	Method	Description
int	compare(GRState s1, GRState s2)	Compares two GRState instances based on their last placed mark.

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.util.Comparator

equals, reversed, thenComparing, thenComparing, thenComparing, thenComparingDouble, thenComparingInt, thenComparingLong

Constructor Details

GRRanking

public GRRanking()

Method Details

compare

public int compare(GRState s1,
 GRState s2)

Compares two GRState instances based on their last placed mark.

A state with a smaller lastMark value is considered better, since it represents a shorter partial ruler.

Specified by:

compare in interface Comparator<GRState>

Parameters:

s1 - the first state to compare.

s2 - the second state to compare.

Returns:

a negative integer if s1 has a smaller last mark than s2, zero if they are equal, or a positive integer otherwise.