private void SearchRec(DomainStore dstore, Sudoku sudoku)
{
// Select the sudoku cell with the smallest domain and try to fill it first
Field f = dstore.GetFieldWithSmallestDomain();
if (f == null)
{
// There's no cell with a domain size > 1 left, the sudoku is filled completely
dstore.UpdateSudoku(sudoku);
return;
}
// Try to solve the sudoku with every possible value of the cell's domain
HashSet <int> domain = dstore.GetDomain(f);
foreach (int digit in domain)
{
DomainStore dstoreClone = new(dstore);
dstoreClone.SetDomain(f, new HashSet <int>()
{
digit
});
Search(dstoreClone, sudoku);
if (sudoku.IsSolved())
{
return;
}
else
{
// Prune this try and take a step back
dstore.UpdateSudoku(sudoku);
}
}
}
private void Search(DomainStore dstore, Sudoku sudoku)
{
if (_cts.IsCancellationRequested)
{
return;
}
// Try to solve sudoku via constraint propagation only
while (Propagate(dstore))
{
}
dstore.UpdateSudoku(sudoku);
if (sudoku.IsSolved())
{
return;
}
// If that didn't work, perform a recursive search
SearchRec(dstore, sudoku);
}