private void SolveCrossTopLayer()
{
// Step 1: Get edges with the color of the top face
IEnumerable <Cube> topEdges = Rubik.Cubes.Where(c => c.IsEdge).Where(c => c.Position.HasFlag(CubeFlag.TopLayer));
// Step 2: Check if the cube is insoluble
if (topEdges.Count(tE => tE.Faces.First(f => f.Position == FacePosition.Top).Color == Rubik.TopColor) % 2 != 0)
{
return;
}
var correctEdges = topEdges.Where(c => c.Faces.First(f => f.Position == FacePosition.Top).Color == Rubik.TopColor);
var solveTopCrossAlgorithmI = new Algorithm("F R U R' U' F'");
var solveTopCrossAlgorithmII = new Algorithm("F S R U R' U' F' S'");
// Step 3: Solve the cross on the top layer
if (Rubik.CountEdgesWithCorrectOrientation() == 0)
{
SolverAlgorithm(solveTopCrossAlgorithmI);
correctEdges = topEdges.Where(c => c.Faces.First(f => f.Position == FacePosition.Top).Color == Rubik.TopColor);
}
if (Rubik.CountEdgesWithCorrectOrientation() == 2)
{
var firstCorrect = correctEdges.First();
var secondCorrect = correctEdges.First(f => f != firstCorrect);
bool opposite = false;
foreach (CubeFlag flag in firstCorrect.Position.GetFlags())
{
CubeFlag pos = CubeFlagService.GetOppositeFlag(flag);
if (secondCorrect.Position.HasFlag(pos) && pos != CubeFlag.None)
{
opposite = true;
break;
}
}
if (opposite)
{
while (correctEdges.Count(c => c.Position.HasFlag(CubeFlag.RightSlice)) != 1)
{
SolverMove(CubeFlag.TopLayer, true);
}
SolverAlgorithm(solveTopCrossAlgorithmI);
}
else
{
while (correctEdges.Count(c => c.Position.HasFlag(CubeFlag.RightSlice) || c.Position.HasFlag(CubeFlag.FrontSlice)) != 2)
{
SolverMove(CubeFlag.TopLayer, true);
}
SolverAlgorithm(solveTopCrossAlgorithmII);
}
}
// Step 4: Move the edges of the cross to their target positions
while (topEdges.Count(c => c.Position.Flags == GetTargetFlags(c)) < 4)
{
IEnumerable <Cube> correctEdges2 = topEdges.Where(c => c.Position.Flags == GetTargetFlags(c));
while (correctEdges2.Count() < 2)
{
SolverMove(CubeFlag.TopLayer, true);
}
CubeFlag rightSlice = CubeFlagService.FromFacePosition(correctEdges2.First().Faces
.First(f => f.Position != FacePosition.Top && f.Color != Color.Black).Position);
SolverMove(CubeFlag.TopLayer, false);
if (correctEdges2.Count(c => c.Position.HasFlag(rightSlice)) == 0)
{
SolverMove(CubeFlag.TopLayer, true);
}
else
{
SolverMove(CubeFlag.TopLayer, true);
rightSlice =
CubeFlagService.FromFacePosition(
correctEdges2
.First(cE => !cE.Position.HasFlag(rightSlice))
.Faces
.First(f =>
f.Position != FacePosition.Top &&
f.Color != Color.Black
)
.Position
);
}
// Algorithm: R U R' U R U U R'
SolverAlgorithm(
"{0} U {0}' U {0} U U {0}'",
CubeFlagService.ToNotationString(rightSlice)
);
while (correctEdges2.Count() < 2)
{
SolverMove(CubeFlag.TopLayer, true);
}
}
}