string Search::solution(string facelets, int maxDepth, long timeOut, bool useSeparator) {
int s = 0;
// +++++++++++++++++++++check for wrong input +++++++++++++++++++++++++++++
int count[6] = {0};
try {
for (int i = 0; i < 54; i++)
{
switch (facelets[i]) {
case 'U':
count[U]++;
break;
case 'R':
count[R]++;
break;
case 'F':
count[F]++;
break;
case 'D':
count[D]++;
break;
case 'L':
count[L]++;
break;
case 'B':
count[B]++;
break;
default:
break;
}
}
} catch (exception e) {
return "Error 1";
}
for (int i = 0; i < 6; i++)
if (count[i] != 9)
return "Error 1";
FaceCube fc = FaceCube(facelets);
auto_ptr<CubieCube> cc = fc.toCubieCube();
if ((s = cc->verify()) != 0){
string result = "Error ";
result += (char)(abs(s)+'0');
return result;
}
// +++++++++++++++++++++++ initialization +++++++++++++++++++++++++++++++++
//---------------------------
CoordCube c = 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;
struct timeval tv;
gettimeofday(&tv,NULL);
long tStart = tv.tv_sec * 1000 + tv.tv_usec / 1000;
// +++++++++++++++++++ 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) {
gettimeofday(&tv,NULL);
if ((tv.tv_sec * 1000 + tv.tv_usec / 1000) - 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::flipMove[flip[n]][mv];
twist[n + 1] = CoordCube::twistMove[twist[n]][mv];
slice[n + 1] = CoordCube::FRtoBR_Move[slice[n] * 24][mv] / 24;
minDistPhase1[n + 1] = 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))
return useSeparator ? solutionToString(s, depthPhase1) : solutionToString(s);
}
}
} while (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.
*
* @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
*/
std::string Search::solution(std::string facelets, int maxDepth, long timeOut, bool useSeparator) {
int s;
// +++++++++++++++++++++check for wrong input +++++++++++++++++++++++++++++
int count[6];
for (int i = 0; i < 6; ++i)
count[i] = 0;
try {
for (int i = 0; i < 54; i++)
++count[FaceCube::charToColor(facelets[i])];
} catch (...) {
return "Error 1";
}
for (int i = 0; i < 6; i++)
if (count[i] != 9)
return "Error 1";
FaceCube fc(facelets);
CubieCube cc(fc.toCubieCube());
if ((s = cc.verify()) != 0) {
char e[40];
sprintf(e, "Error %d", abs(s));
return e;
}
// +++++++++++++++++++++++ initialization +++++++++++++++++++++++++++++++++
CoordCube c(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 = 1, n = 0;
bool busy = false; // gets set when a move is popped from the stack
int depthPhase1 = 1;
clock_t tStart = clock();
timeOut *= CLOCKS_PER_SEC;
// +++++++++++++++++++ Main loop ++++++++++++++++++++++++++++++++++++++++++
do {
/* Find the next node to test
* This is an Iterative Deepening A* search (IDA*)
* which means we are doing a depth first search over and over again
* with increasing depth limit while pruning branches which would
* give too many total moves.
*
* n is current depth
* depthPhase1 is current max depth
* minDistPhase1[n + 1] is the pruning value which gives a lower bound
* on the moves necessary after the current move
*
* the sequence of moves are stored as ax[] and po[] which together represents each move.
* ax[n] is the axis, 0 to 2
* po[n] is the power, 1 to 15 (which combination of moves on the axis)
*/
do { // loop for choice of node while busy
if ((n + minDistPhase1[n + 1] < depthPhase1) && !busy) {
// Dig deeper
// Initialize next move, avoid previous axis
if (ax[n] != 0)
ax[++n] = 0;
else
ax[++n] = 1;
po[n] = 1;
} else if (++po[n] > 15) { // increment power
do {// increment axis
if (++ax[n] > 2) {
if (clock() - tStart > timeOut)
return "Error 8";
if (n == 0) {
if (depthPhase1 >= maxDepth)
return "Error 7";
else {
// Start over with greater depth
depthPhase1++;
ax[n] = 0;
po[n] = 1;
busy = false;
break;
}
} else {
// Decrease current depth
n--;
busy = true;
break;
}
} else {
po[n] = 1;
busy = false;
}
} while (n != 0 && (ax[n - 1] == ax[n]));
} else
busy = false;
} while (busy);
// +++++++++++++ compute new coordinates and new minDistPhase1 ++++++++++
// if minDistPhase1 =0, the H subgroup is reached
mv = 16 * ax[n] + po[n];
if (mv > CoordCube::N_MOVE)
printf("n: %d ax[n]: %d po[n]: %d mv: %d ", n, ax[n], po[n], mv);
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;
minDistPhase1[n + 1] = std::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))
return useSeparator ? solutionToString(s, depthPhase1) : solutionToString(s);
}
}
} while (true);
}