protected override void OperateOn(SudokuModel model)
{
for (var iType = 0; iType < 3; ++iType) {
var type = (RegionType)iType;
for (var i = 0; i < model.Size; ++i) {
var region = new Region(type, i);
var tuple = new Tuple<SudokuModel, Region>(model, region);
if (GetCheckedIteration(tuple) < model.GetLastChangedIterRegion(type, i)) {
_checkedIteration[tuple] = model.ChangeCount;
foreach (var unsolved in model.GetUnsolvedValues(type, i)) {
var timesFound = 0;
Cell? foundAt = null;
foreach (var cell in model.GetCells(type, i)) {
if ((model.GetPossibilitySetCell(cell.Column, cell.Row) & (1 << unsolved)) != 0) {
++timesFound;
foundAt = cell;
if (timesFound > 1) {
break;
}
}
}
if (timesFound == 1) {
if (foundAt != null) {
model.SetValueOptimized(foundAt.Value.Column, foundAt.Value.Row, unsolved, type, i);
}
}
}
}
}
}
}
public static void EliminateDuplicates(SudokuModel model, int col, int row)
{
if (model.IsSolved(col, row)) {
var value = model.GetValue(col, row);
foreach (var region in model.GetIntersectingRegions(col, row)) {
foreach (var other in model.GetCells(region.Type, region.I)) {
if (other.Column != col || other.Row != row) {
model.Eliminate(other.Column, other.Row, value);
}
}
}
}
}
static void IsolateSet(int set, Region region, SudokuModel model)
{
var cells = model.GetCells(region.Type, region.I);
var cellsNotContainedBySet = cells.Where(cell => (model.GetPossibilitySetCell(cell.Column, cell.Row) | set) != set).ToList();
var numCellsContainedBySet = cells.Length - cellsNotContainedBySet.Count;
if (numCellsContainedBySet != set.HiBitCount()) {
return;
}
// we now know that each of the numbers in the set must be exclusively in
// one of the contained cells, so we eliminate that set from all other cells'
// possibility bits.
var mask = ~set;
foreach (var cell in cellsNotContainedBySet) {
var poss = model.GetPossibilitySetCell(cell.Column, cell.Row);
model.SetPossibilitySetCell(cell.Column, cell.Row, poss & mask);
}
}