h12

package aima.core.environment.eightpuzzle;

import aima.core.search.framework.HeuristicFunction;
import aima.core.util.datastructure.XYLocation;

/**
 * @author Ravi Mohan
 *
 */
public class Heuristic12 implements HeuristicFunction {

	private EightPuzzleGoalTest goal;

	public Heuristic12(EightPuzzleGoalTest goal) {
		this.goal = goal;
	}

	public double h(Object state) {
		EightPuzzleBoard board = (EightPuzzleBoard) state;
		int retVal = 0;
		for (int i = 1; i < 9; i++) {
			XYLocation loc = board.getLocationOf(i);
			XYLocation locGS = goal.getLocationOf(i);
			retVal += evaluateDistanceOf(loc, locGS);
		}
		return retVal;

	}

	public int evaluateDistanceOf(XYLocation loc, XYLocation locGS) {
		int retVal = 0;
		int xpos = loc.getXCoOrdinate();
		int ypos = loc.getYCoOrdinate();
		int xposGS = locGS.getXCoOrdinate();
		int yposGS = locGS.getYCoOrdinate();

		if (xpos != xposGS) retVal += 1;
		if (ypos != yposGS) retVal +=1;

		return retVal;
	}
}