/**
* Generate a random 2x2 position.
* @param r random int generator
*/
public TwoByTwoState RandomState(Random r)
{
TwoByTwoState state = new TwoByTwoState();
state.Permutation = r.Next(N_PERM);
state.Orientation = r.Next(N_ORIENT);
return(state);
}
private string Solve(TwoByTwoState state, int desiredLength, bool exactLength, bool inverse)
{
int[] solution = new int[MAX_LENGTH];
int[] best_solution = new int[MAX_LENGTH + 1];
bool foundSolution = false;
int length = exactLength ? desiredLength : 0;
while (length <= desiredLength)
{
best_solution[length] = 42424242;
if (Search(state.Permutation, state.Orientation, 0, length, 42, solution, best_solution))
{
foundSolution = true;
break;
}
length++;
}
if (!foundSolution)
{
return(null);
}
if (length == 0)
{
return("");
}
StringBuilder scramble = new StringBuilder(MAX_LENGTH * 3);
if (inverse)
{
scramble.Append(inverseMoveToString[best_solution[length - 1]]);
for (int l = length - 2; l >= 0; l--)
{
scramble.Append(" ").Append(inverseMoveToString[best_solution[l]]);
}
}
else
{
scramble.Append(moveToString[best_solution[0]]);
for (int l = 1; l < length; l++)
{
scramble.Append(" ").Append(moveToString[best_solution[l]]);
}
}
return(scramble.ToString());
}
public TwoByTwoState ToTwoByTwoState()
{
var state = new TwoByTwoState();
var stickersByPiece = GetStickersByPiece(_image);
// Here's a clever color value assigning system that gives each piece
// a unique id just by summing up the values of its stickers.
//
// +----------+
// |*3* *2*|
// | U (0) |
// |*1* *0*|
// +----------+----------+----------+----------+
// | 3 1 | 1 0 | 0 2 | 2 3 |
// | L (1) | F (0) | R (0) | B (2) |
// | 7 5 | 5 4 | 4 6 | 6 7 |
// +----------+----------+----------+----------+
// |*5* *4*|
// | D (4) |
// |*7* *6*|
// +----------+
//
var dColor = stickersByPiece[7][0];
var bColor = stickersByPiece[7][1];
var lColor = stickersByPiece[7][2];
var uColor = (int)((Face)dColor).OppositeFace();
var fColor = (int)((Face)bColor).OppositeFace();
var rColor = (int)((Face)lColor).OppositeFace();
var colorToVal = new int[8];
colorToVal[uColor] = 0;
colorToVal[fColor] = 0;
colorToVal[rColor] = 0;
colorToVal[lColor] = 1;
colorToVal[bColor] = 2;
colorToVal[dColor] = 4;
var pieces = new int[7];
for (var i = 0; i < pieces.Length; i++)
{
var stickers = stickersByPiece[i];
var pieceVal = colorToVal[stickers[0]] + colorToVal[stickers[1]] + colorToVal[stickers[2]];
var clockwiseTurnsToGetToPrimaryColor = 0;
while (stickers[clockwiseTurnsToGetToPrimaryColor] != uColor &&
stickers[clockwiseTurnsToGetToPrimaryColor] != dColor)
{
clockwiseTurnsToGetToPrimaryColor++;
azzert(clockwiseTurnsToGetToPrimaryColor < 3);
}
var piece = (clockwiseTurnsToGetToPrimaryColor << 3) + pieceVal;
pieces[i] = piece;
}
state.Permutation = TwoByTwoSolver.PackPerm(pieces);
state.Orientation = TwoByTwoSolver.PackOrient(pieces);
return(state);
}
/**
* Return a generator of a given position in exactly length number of turns or not at all.
* Returns either the solution or the generator (inverse solution)
* @param perm permutation
* @param orient random int generator
* @param length length of the desired solution
* @return a string representing the solution or the scramble of a random position
*/
public string GenerateExactly(TwoByTwoState state, int length)
{
return(Solve(state, length, true, true));
}
/**
* Solve a given position in less than or equal to length number of turns.
* Returns either the solution or the generator (inverse solution)
* @param state state
* @param length length of the desired solution
* @return a string representing the solution or the scramble of a random position
*/
public string SolveIn(TwoByTwoState state, int length)
{
return(Solve(state, length, false, false));
}