Magic Cube

package org.distorted.solvers.cube3;

import android.content.res.Resources;

import android.util.Log;

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

/**

 * Class Search implements the Two-Phase-Algorithm.

 */

public class Search {

	static boolean mInterrupted;

	static int mNumMoves = 0;

	static int[] ax = new int[31]; // The axis of the move

	static int[] po = new int[31]; // The power of the move

	static int[] flip = new int[31]; // phase1 coordinates

	static int[] twist = new int[31];

	static int[] slice = new int[31];

	static int[] parity = new int[31]; // phase2 coordinates

	static int[] URFtoDLF = new int[31];

	static int[] FRtoBR = new int[31];

	static int[] URtoUL = new int[31];

	static int[] UBtoDF = new int[31];

	static int[] URtoDF = new int[31];

	static int[] minDistPhase1 = new int[31]; // IDA* distance do goal estimations

	static int[] minDistPhase2 = new int[31];

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

	// retyurn number of moves in the already computed solution

	public static int numMoves() 

	{

		return mNumMoves;

	}

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

	// generate the solution string from the array data

	static String solutionToString(int length) 

	{

		String s = "";

		for (int i = 0; i < length; i++) {

			switch (ax[i]) {

			case 0: switch(po[i])

			          {

			          case 1: s+=" 363"; break;

			          case 2: s+=" 364"; break;

			          case 3: s+=" 361"; break;

			          }

				    break;

			case 1: switch(po[i])

	                  {

	                  case 1: s+=" 043"; break;

	                  case 2: s+=" 044"; break;

	                  case 3: s+=" 041"; break;

	                  }

				    break;

			case 2: switch(po[i])

                      {

                      case 1: s+=" 683"; break;

                      case 2: s+=" 684"; break;

                      case 3: s+=" 681"; break;

                      }

				    break;

			case 3: switch(po[i])

                      {

                      case 1: s+=" 331"; break;

                      case 2: s+=" 330"; break;

                      case 3: s+=" 333"; break;

                      }

				    break;

			case 4: switch(po[i])

                      {

                      case 1: s+=" 011"; break;

                      case 2: s+=" 010"; break;

                      case 3: s+=" 013"; break;

                      }

				    break;

			case 5: switch(po[i])

                      {

                      case 1: s+=" 651"; break;

                      case 2: s+=" 650"; break;

                      case 3: s+=" 653"; break;

                      }

				    break;

			}		

		}

		return s;

	};

	/**

	 * Interrupt current computation

	 */

	public static void interrupt()

	{

		mInterrupted = true;

	}

	/**

	 * Prepare pruning tables

	 */

	public static boolean prepare(Resources res)

	{

	  if( mInterrupted ) return false;

	  CoordCube.initialize1(res);

	  if( mInterrupted ) return false;

	  CoordCube.initialize2(res);

	  if( mInterrupted ) return false;

	  CoordCube.initialize3(res);

	  if( mInterrupted ) return false;

	  CoordCube.initialize4(res);

	  if( mInterrupted ) return false;

	  CoordCube.initialize5(res);

	  if( mInterrupted ) return false;

	  CoordCube.initialize6(res);

	  if( mInterrupted ) return false;

	  CoordCube.initialize7(res);

	  if( mInterrupted ) return false;

	  CoordCube.initialize8(res);

	  if( mInterrupted ) return false;

	  CoordCube.initialize9(res);

	  if( mInterrupted ) return false;

	  CoordCube.initialize10(res);

	  if( mInterrupted ) return false;

	  CoordCube.initialize11(res);

	  if( mInterrupted ) return false;

	  CoordCube.initialize12(res);

	  if( mInterrupted ) return false;

	  return true;

	}

	/**

	 * Computes the solver string for a given cube.

	 * 

	 * @param facelets

	 *          is the cube definition string, see {@link Facelet} for the format.

	 * 

	 * @param maxDepth

	 *          defines the maximal allowed maneuver length. For random cubes, a maxDepth of 21 usually will return a

	 *          solution in less than 0.5 seconds. With a maxDepth of 20 it takes a few seconds on average to find a

	 *          solution, but it may take much longer for specific cubes.

	 * 

	 *@param timeOut

	 *          defines the maximum computing time of the method in seconds. If it does not return with a solution, it returns with

	 *          an error code.

	 * @return The solution string or an error code:<br>

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

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

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

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

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

	 *         Error 6: Parity error: Two corners or two edges have to be exchanged<br>

	 *         Error 7: No solution exists for the given maxDepth<br>

	 *         Error 8: Timeout, no solution within given time

	 */

	public static String solution(String facelets, int maxDepth, long timeOut) 

	    {

		int s;

		mInterrupted = false;

		// +++++++++++++++++++++check for wrong input +++++++++++++++++++++++++++++

		int[] count = new int[6];

		try {

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

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

		} catch (Exception e) {Log.d("error", "1");

			return "Error 1";

		}

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

			if (count[i] != 9)  { Log.d("error", "2");

				return "Error 1"; }

		FaceCube fc = new FaceCube(facelets);

		CubieCube cc = fc.toCubieCube();

		if ((s = cc.verify()) != 0)   { Log.d("error", "3");

			return "Error " + Math.abs(s); }

		// +++++++++++++++++++++++ initialization +++++++++++++++++++++++++++++++++

		CoordCube c = new CoordCube(cc);

		po[0] = 0;

		ax[0] = 0;

		flip[0] = c.flip;

		twist[0] = c.twist;

		parity[0] = c.parity;

		slice[0] = c.FRtoBR / 24;

		URFtoDLF[0] = c.URFtoDLF;

		FRtoBR[0] = c.FRtoBR;

		URtoUL[0] = c.URtoUL;

		UBtoDF[0] = c.UBtoDF;

		minDistPhase1[1] = 1;// else failure for depth=1, n=0

		int mv = 0, n = 0;

		boolean busy = false;

		int depthPhase1 = 1;

		long tStart = System.currentTimeMillis();

		// +++++++++++++++++++ Main loop ++++++++++++++++++++++++++++++++++++++++++

		do {

			do {

				if( mInterrupted ) return "Error 9";

				if ((depthPhase1 - n > minDistPhase1[n + 1]) && !busy) {

					if (ax[n] == 0 || ax[n] == 3)// Initialize next move

						ax[++n] = 1;

					else

						ax[++n] = 0;

					po[n] = 1;

				} else if (++po[n] > 3) {

					do {// increment axis

						if (++ax[n] > 5) {

							if (System.currentTimeMillis() - tStart > timeOut << 10)

								return "Error 8";

							if (n == 0) {

								if (depthPhase1 >= maxDepth)

									return "Error 7";

								else {

									depthPhase1++;

									ax[n] = 0;

									po[n] = 1;

									busy = false;

									break;

								}

							} else {

								n--;

								busy = true;

								break;

							}

						} else {

							po[n] = 1;

							busy = false;

						}

					} while (n != 0 && (ax[n - 1] == ax[n] || ax[n - 1] - 3 == ax[n]));

				} else

					busy = false;

			} while (busy);

			// +++++++++++++ compute new coordinates and new minDistPhase1 ++++++++++

			// if minDistPhase1 =0, the H subgroup is reached

			mv = 3 * ax[n] + po[n] - 1;

			flip[n + 1] = CoordCube.getFlipMove(flip[n],mv);

			twist[n + 1] = CoordCube.getTwistMove(twist[n],mv);

			slice[n + 1] = CoordCube.getFRtoBR_Move(slice[n] * 24,mv) / 24;

			minDistPhase1[n + 1] = Math.max(CoordCube.getPruning(CoordCube.Slice_Flip_Prun, CoordCube.N_SLICE1 * flip[n + 1]

					+ slice[n + 1]), CoordCube.getPruning(CoordCube.Slice_Twist_Prun, CoordCube.N_SLICE1 * twist[n + 1]

					+ slice[n + 1]));

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

			if (minDistPhase1[n + 1] == 0 && n >= depthPhase1 - 5) {

				minDistPhase1[n + 1] = 10;// instead of 10 any value >5 is possible

				if (n == depthPhase1 - 1 && (s = totalDepth(depthPhase1, maxDepth)) >= 0) {

					if (s == depthPhase1 || (ax[depthPhase1 - 1] != ax[depthPhase1] && ax[depthPhase1 - 1] != ax[depthPhase1] + 3))

					{

						mNumMoves = s;

						return solutionToString(s);

					}

				}

			}

		} while (true);

	}

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

	// Apply phase2 of algorithm and return the combined phase1 and phase2 depth. In phase2, only the moves

	// U,D,R2,F2,L2 and B2 are allowed.

	static int totalDepth(int depthPhase1, int maxDepth) {

		int mv = 0, d1 = 0, d2 = 0;

		int maxDepthPhase2 = Math.min(10, maxDepth - depthPhase1);// Allow only max 10 moves in phase2

		for (int i = 0; i < depthPhase1; i++) {

			mv = 3 * ax[i] + po[i] - 1;

			URFtoDLF[i + 1] = CoordCube.getURFtoDLF_Move(URFtoDLF[i],mv);

			FRtoBR[i + 1] = CoordCube.getFRtoBR_Move(FRtoBR[i],mv);

			parity[i + 1] = CoordCube.parityMove[parity[i]][mv];

		}

		if ((d1 = CoordCube.getPruning(CoordCube.Slice_URFtoDLF_Parity_Prun,

				(CoordCube.N_SLICE2 * URFtoDLF[depthPhase1] + FRtoBR[depthPhase1]) * 2 + parity[depthPhase1])) > maxDepthPhase2)

			return -1;

		for (int i = 0; i < depthPhase1; i++) {

			mv = 3 * ax[i] + po[i] - 1;

			URtoUL[i + 1] = CoordCube.getURtoUL_Move(URtoUL[i],mv);

			UBtoDF[i + 1] = CoordCube.getUBtoDF_Move(UBtoDF[i],mv);

		}

		URtoDF[depthPhase1] = CoordCube.getMergeURtoULandUBtoDF(URtoUL[depthPhase1],UBtoDF[depthPhase1]);

		if ((d2 = CoordCube.getPruning(CoordCube.Slice_URtoDF_Parity_Prun,

				(CoordCube.N_SLICE2 * URtoDF[depthPhase1] + FRtoBR[depthPhase1]) * 2 + parity[depthPhase1])) > maxDepthPhase2)

			return -1;

		if ((minDistPhase2[depthPhase1] = Math.max(d1, d2)) == 0)// already solved

			return depthPhase1;

		// now set up search

		int depthPhase2 = 1;

		int n = depthPhase1;

		boolean busy = false;

		po[depthPhase1] = 0;

		ax[depthPhase1] = 0;

		minDistPhase2[n + 1] = 1;// else failure for depthPhase2=1, n=0

		// +++++++++++++++++++ end initialization +++++++++++++++++++++++++++++++++

		do {

			do {

				if ((depthPhase1 + depthPhase2 - n > minDistPhase2[n + 1]) && !busy) {

					if (ax[n] == 0 || ax[n] == 3)// Initialize next move

					{

						ax[++n] = 1;

						po[n] = 2;

					} else {

						ax[++n] = 0;

						po[n] = 1;

					}

				} else if ((ax[n] == 0 || ax[n] == 3) ? (++po[n] > 3) : ((po[n] = po[n] + 2) > 3)) {

					do {// increment axis

						if (++ax[n] > 5) {

							if (n == depthPhase1) {

								if (depthPhase2 >= maxDepthPhase2)

									return -1;

								else {

									depthPhase2++;

									ax[n] = 0;

									po[n] = 1;

									busy = false;

									break;

								}

							} else {

								n--;

								busy = true;

								break;

							}

						} else {

							if (ax[n] == 0 || ax[n] == 3)

								po[n] = 1;

							else

								po[n] = 2;

							busy = false;

						}

					} while (n != depthPhase1 && (ax[n - 1] == ax[n] || ax[n - 1] - 3 == ax[n]));

				} else

					busy = false;

			} while (busy);

			// +++++++++++++ compute new coordinates and new minDist ++++++++++

			mv = 3 * ax[n] + po[n] - 1;

			URFtoDLF[n + 1] = CoordCube.getURFtoDLF_Move(URFtoDLF[n],mv);

			FRtoBR[n + 1] = CoordCube.getFRtoBR_Move(FRtoBR[n],mv);

			parity[n + 1] = CoordCube.parityMove[parity[n]][mv];

			URtoDF[n + 1] = CoordCube.getURtoDF_Move(URtoDF[n],mv);

			minDistPhase2[n + 1] = Math.max(CoordCube.getPruning(CoordCube.Slice_URtoDF_Parity_Prun, (CoordCube.N_SLICE2

					* URtoDF[n + 1] + FRtoBR[n + 1])

					* 2 + parity[n + 1]), CoordCube.getPruning(CoordCube.Slice_URFtoDLF_Parity_Prun, (CoordCube.N_SLICE2

					* URFtoDLF[n + 1] + FRtoBR[n + 1])

					* 2 + parity[n + 1]));

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

		} while (minDistPhase2[n + 1] != 0);

		return depthPhase1 + depthPhase2;

	}

}