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);
}
}
}
}
}
}
}
int GetCheckedIteration(Region region)
{
if (!_checkedIteration.ContainsKey(region)) {
_checkedIteration[region] = -1;
}
return _checkedIteration[region];
}
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);
}
}
/// <summary>
/// Returns the Row, Column, and Square that contain that cell.
/// </summary>
public IEnumerable<Region> GetIntersectingRegions(int col, int row)
{
if (_intersectingRegions[col, row] == null) {
_intersectingRegions[col, row] = new Region[3];
_intersectingRegions[col, row][0] = new Region(RegionType.Column, col);
_intersectingRegions[col, row][1] = new Region(RegionType.Row, row);
int sqI = (row / _sizeSqrt) * _sizeSqrt + col / _sizeSqrt;
_intersectingRegions[col, row][2] = new Region(RegionType.Square, sqI);
}
return _intersectingRegions[col, row];
}
