private bool SolveHelper(Board board)
{
// Create Reducers
OtherRowsAreBlockedReducer otherRowsAreBlockedReducer = new OtherRowsAreBlockedReducer(board);
OtherColumnsAreBlockedReducer otherColumnsAreBlockedReducer = new OtherColumnsAreBlockedReducer(board);
EqualOptionsInRowReducer equalOptionsInRowReducer = new EqualOptionsInRowReducer(board);
EqualOptionsInColumnReducer equalOptionsInColumnReducer = new EqualOptionsInColumnReducer(board);
EqualOptionsInQuadReducer equalOptionsInQuadReducer = new EqualOptionsInQuadReducer(board);
// Create Solvers
OnlyCandidateInCellSolver onlyCandidateInCellSolver = new OnlyCandidateInCellSolver(board);
OnlyOptionInRowSolver onlyOptionInRowSolver = new OnlyOptionInRowSolver(board);
OnlyOptionInColumnSolver onlyOptionInColumnSolver = new OnlyOptionInColumnSolver(board);
OnlyOptionInQuadSolver onlyOptionInQuadSolver = new OnlyOptionInQuadSolver(board);
while (true)
{
iterations++;
bool repeatLoop = false;
// Limit insertion candidates
repeatLoop = repeatLoop || otherRowsAreBlockedReducer.Run();
repeatLoop = repeatLoop || otherColumnsAreBlockedReducer.Run();
repeatLoop = repeatLoop || equalOptionsInRowReducer.Run();
repeatLoop = repeatLoop || equalOptionsInColumnReducer.Run();
repeatLoop = repeatLoop || equalOptionsInQuadReducer.Run();
// Fill cells
repeatLoop = repeatLoop || onlyCandidateInCellSolver.Run();
repeatLoop = repeatLoop || onlyOptionInRowSolver.Run();
repeatLoop = repeatLoop || onlyOptionInColumnSolver.Run();
repeatLoop = repeatLoop || onlyOptionInQuadSolver.Run();
if (repeatLoop)
{
continue;
}
if (board.UnknownValues() == 0)
{
return(true);
}
else if (board.BacktrackLevel < maxBacktrackLevel)
{
foreach (Cell cell in board.AllCells())
{
foreach (int candidate in cell.Candidates)
{
Board newBoard = new Board(board);
Cell assumedCell = new Cell(cell);
assumedCell.Number = candidate;
newBoard.ReplaceCell(assumedCell);
if (SolveHelper(newBoard))
{
assumedCells.Add(assumedCell);
foreach (Cell solvedCell in newBoard.AllCells())
{
board.ReplaceCell(solvedCell);
}
return(true);
}
}
}
}
return(false);
}
}