private bool DeleteField(Sudoku temp, ref int difficulty)
{
int i = Rnd.Next(0, 9); ;
int j = Rnd.Next(0, 9); ;
// select random not yet deleted field
while (!temp.Fields[i][j].Filled)
{
i = Rnd.Next(0, 9);
j = Rnd.Next(0, 9);
}
temp.Fields[i][j].Value = 0;
temp.Fields[i][j].Filled = false;
SudokuSolver Test = new SudokuSolver();
int Difficulty = difficulty;
// check the desired characteristics
Sudoku Temp = Test.Solve(temp.Copy(), true, Difficulty);
if (Temp == null)
return false;
temp.Difficulty = Temp.Difficulty;
if (Temp.NrSolutions > 1 || Temp.Difficulty > Difficulty)
return false;
else
return true;
}
private void BruteForce(List<Sudoku.Field> ToDo, int pos, Sudoku Temp, bool count)
{
if (Finished)
return;
for (int i = 0; i < ToDo[pos].Candidates.Count; i++)
{
Sudoku Copied = Temp.Copy();
Copied.Fields[ToDo[pos].i][ToDo[pos].j].Filled = true;
Copied.Fields[ToDo[pos].i][ToDo[pos].j].NewFound = false;
// place a random value and ...
Copied.Fields[ToDo[pos].i][ToDo[pos].j].Value = ToDo[pos].Candidates[i];
bool Valid = true;
// ... check if solution is still valid
foreach (Sudoku.Field f in Copied.GetGroup(ToDo[pos].i, ToDo[pos].j))
{
if (f.Filled && f.Value == Copied.Fields[ToDo[pos].i][ToDo[pos].j].Value)
{
Valid = false;
break;
}
}
if (Valid)
{ // if yes, go to the next position
if (pos % 5 == 0)
Grade0();
if (pos < ToDo.Count - 1)
BruteForce(ToDo, pos + 1, Copied, count);
else
{ // or otherwise, we are done
if (!count)
{
Finished = true;
Input = Copied;
Remaining = 0;
}
else
{ // if we want to count the solutions, we do not stop after having found the first one
SolCounter++;
Remaining = 0;
if (SolCounter > 1)
{
Finished = true;
}
}
}
}
}
}
private void BruteForce(List<Sudoku.Field> ToDo, int pos, Sudoku Temp)
{
// the brute force implementation for creating complete sudokus
if (Finished)
return;
for (int i = 1; i <= 9; i++)
{
Sudoku Copied = Temp.Copy();
Copied.Fields[ToDo[pos].i][ToDo[pos].j].Filled = true;
Copied.Fields[ToDo[pos].i][ToDo[pos].j].Value = Rnd.Next(1, 10);
bool Valid = true;
foreach (Sudoku.Field f in Copied.GetGroup(ToDo[pos].i, ToDo[pos].j))
{
if (f.Filled && f.Value == Copied.Fields[ToDo[pos].i][ToDo[pos].j].Value)
{
Valid = false;
break;
}
}
if (Valid)
{
if (pos < ToDo.Count - 1)
BruteForce(ToDo, pos + 1, Copied);
else
{
Finished = true;
Result = Copied;
}
}
}
}