// ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
// 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++)
{
Color col;
if (!Enum.TryParse(s.Substring(i, 1), out col))
{
throw new Exception("Invalid color");
}
count[(int)col]++;
}
}
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.Next(CoordCube.N_FLIP));
cc.setTwist((short)gen.Next(CoordCube.N_TWIST));
do
{
cc.setURFtoDLB(gen.Next(CoordCube.N_URFtoDLB));
cc.setURtoBR(gen.Next(CoordCube.N_URtoBR));
} while ((cc.edgeParity() ^ cc.cornerParity()) != 0);
FaceCube fc = cc.toFaceCube();
return(fc.to_String());
}
/**
* 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.
*
* @param useSeparator
* determines if a " . " separates the phase1 and phase2 parts of the solver string like in F' R B R L2 F .
* U2 U D for example.<br>
* @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, bool useSeparator)
{
int s;
// +++++++++++++++++++++check for wrong input +++++++++++++++++++++++++++++
int[] count = new int[6];
try
{
for (int i = 0; i < 54; i++)
{
Color col;
if (!Enum.TryParse(facelets.Substring(i, 1), out col))
{
throw new Exception("Invalid color");
}
count[(int)col]++;
}
}
catch (Exception e)
{
return("Error 1");
}
for (int i = 0; i < 6; i++)
{
if (count[i] != 9)
{
return("Error 1");
}
}
FaceCube fc = new FaceCube(facelets);
CubieCube cc = fc.toCubieCube();
if ((s = cc.verify()) != 0)
{
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;
bool busy = false;
int depthPhase1 = 1;
// +++++++++++++++++++ Main loop ++++++++++++++++++++++++++++++++++++++++++
do
{
do
{
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 (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.flipMove[flip[n], mv];
twist[n + 1] = CoordCube.twistMove[twist[n], mv];
slice[n + 1] = CoordCube.FRtoBR_Move[slice[n] * 24, mv] / 24;
sbyte[] table = CoordCube.Slice_Flip_Prun;
int index = CoordCube.N_SLICE1 * flip[n + 1]
+ slice[n + 1];
sbyte[] table1 = CoordCube.Slice_Twist_Prun;
int index1 = CoordCube.N_SLICE1 * twist[n + 1]
+ slice[n + 1];
minDistPhase1[n + 1] = Math.Max((index % 2 == 0) ? (table[index >> 1] & 0x0f) : ((table[index >> 1] & 0xf0) >> 4), (index1 % 2 == 0) ? (table1[index1 >> 1] & 0x0f) : ((table1[index1 >> 1] & 0xf0) >> 4));
// ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
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))
{
return(useSeparator ? solutionToString(s, depthPhase1) : solutionToString(s));
}
}
}
} while (true);
}