private SolutionInfo CheckCellValuesForViability(OpenCell cell)
{
// debugLog.Write("CheckCellValuesForViability(" + cell.ToString() + ")");
SolutionInfo solutionInfo = new SolutionInfo();
int sumOfUnsolvedCels = SumOfAllUnsolvedCells();
if (sumOfUnsolvedCels == 0)
{
solutionInfo.solvable = false;
return(solutionInfo);
}
List <int> possibleDigits = new List <int>(cell.GetPossibleValues());
int initialNumberOfDigits = cell.GetPossibleValues().Count;
List <OpenCell> copyOfUnsolvedCellList = data.GetCopyOfUnsolvedCells();
copyOfUnsolvedCellList.Remove(cell);
Stack <OpenCell> cellStack = new Stack <OpenCell>(copyOfUnsolvedCellList);
foreach (int digit in possibleDigits)
{
if (digit <= sumOfUnsolvedCels)
{
List <int> availableDigitsFromGroup = new List <int>(data.availableDigits);
availableDigitsFromGroup.Remove(digit);
if (!SumWorksForGroup(sumOfUnsolvedCels - digit, availableDigitsFromGroup, cellStack))
{
cell.DigitIsNotAPossibleValue(digit);
}
}
else
{
cell.DigitIsNotAPossibleValue(digit);
}
}
int finalNumberOfDigits = cell.GetPossibleValues().Count;
solutionInfo.increaseInNumber = finalNumberOfDigits - initialNumberOfDigits;
debugLog.Write(" Validate cell " + cell.ToString() +
"(start:" + initialNumberOfDigits + " end:" + finalNumberOfDigits + ")\n");
if (finalNumberOfDigits == 0)
{
solutionInfo.solvable = false;
}
return(solutionInfo);
}
private bool SolveForLastCell()
{
debugLog.Write("Only one cell to try. Solving that cell...\n");
OpenCell cellToSolve = data.GetCopyOfUnsolvedCells().ElementAt(0);
int randomValue = cellToSolve.GetARandomValue();
if (randomValue == 0)
{
return(false);
}
int sum = SumOfAllSolvedCells() + randomValue;
if (data.unusableSums.Contains(sum))
{
cellToSolve.DigitIsNotAPossibleValue(randomValue);
return(SolveForLastCell());
}
cellToSolve.SetToAValue(randomValue);
FinalizeBothParents(cellToSolve);
return(UpdateSum(sum)); // Need to deal with a failure here...
}