Magic Cube

package org.distorted.solvers.cube3;

import java.util.Random;

public class Tools {

	// ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

	// Check if the cube string s represents a solvable cube.

	// 0: Cube is solvable

	// -1: There is not exactly one facelet of each colour

	// -2: Not all 12 edges exist exactly once

	// -3: Flip error: One edge has to be flipped

	// -4: Not all corners exist exactly once

	// -5: Twist error: One corner has to be twisted

	// -6: Parity error: Two corners or two edges have to be exchanged

	// 

	/**

	 * Check if the cube definition string s represents a solvable cube.

	 * 

	 * @param s is the cube definition string , see {@link Facelet}

	 * @return 0: Cube is solvable<br>

	 *         -1: There is not exactly one facelet of each colour<br>

	 *         -2: Not all 12 edges exist exactly once<br>

	 *         -3: Flip error: One edge has to be flipped<br>

	 *         -4: Not all 8 corners exist exactly once<br>

	 *         -5: Twist error: One corner has to be twisted<br>

	 *         -6: Parity error: Two corners or two edges have to be exchanged

	 */

	public static int verify(String s) {

		int[] count = new int[6];

		try {

			for (int i = 0; i < 54; i++)

				count[Color.toInt(s.substring(i, i + 1))]++;

		} catch (Exception e) {

			return -1;

		}

		for (int i = 0; i < 6; i++)

			if (count[i] != 9)

				return -1;

		FaceCube fc = new FaceCube(s);

		CubieCube cc = fc.toCubieCube();

		return cc.verify();

	}

	/**

	 * Generates a random cube.

	 * @return A random cube in the string representation. Each cube of the cube space has the same probability.

	 */

	public static String randomCube() {

		CubieCube cc = new CubieCube();

		Random gen = new Random();

		cc.setFlip((short) gen.nextInt(CoordCube.N_FLIP));

		cc.setTwist((short) gen.nextInt(CoordCube.N_TWIST));

		do {

			cc.setURFtoDLB(gen.nextInt(CoordCube.N_URFtoDLB));

			cc.setURtoBR(gen.nextInt(CoordCube.N_URtoBR));

		} while ((cc.edgeParity() ^ cc.cornerParity()) != 0);

		FaceCube fc = cc.toFaceCube();

		return fc.to_String();

	}

}