/// <summary>
/// checks for if the puzzle is valid in the sense that is has more than 7 unique numbers at any point in the puzzle, more than 16 givens, and one solution
/// </summary>
/// <param name="grid"></param>
/// <returns></returns>
public bool CheckValidity(SudokuGrid grid)
{
bool minOfEight = false;
int givens = 0;
List <char> numList = new List <char> {
'1', '2', '3', '4', '5', '6', '7', '8', '9'
};
for (int x = 0; x < 9; x++)
{
for (int y = 0; y < 9; y++)
{
if (grid.Cells[x][y].Num != '0')
{
numList.Remove(grid.Cells[x][y].Num);
if (numList.Count <= 1)
{
minOfEight = true;
}
givens++;
}
}
}
if (!minOfEight || givens < 17)
{
return(false);
}
char[][] sudokuArray = new char[9][] { new char[9], new char[9], new char[9], new char[9], new char[9], new char[9], new char[9], new char[9], new char[9] };
for (int r = 0; r < 9; r++)
{
for (int c = 0; c < 9; c++)
{
sudokuArray[r][c] = grid.Cells[r][c].Num;
}
}
PuzzleSolverAdvDS solve = new PuzzleSolverAdvDS();
if (solve.CompileBacktracker(grid, 4))
{
string firstSol = GridToString(grid);
grid = RestartPuzzle(grid, sudokuArray);
if (solve.CompileBacktracker(grid, 1))
{
string secSol = GridToString(grid);
if (firstSol == secSol)//valid puzzle
{
grid = RestartPuzzle(grid, sudokuArray);
return(true);
}
else
{
grid = RestartPuzzle(grid, sudokuArray);
return(false);
}
}
}
return(true);
}
/// <summary>
///
/// </summary>
/// <returns>the puzzle in form of SudokuGrid</returns>
public SudokuGrid Setter()
{
PuzzleSolverAdvDS solve = new PuzzleSolverAdvDS();
SudokuGrid grid = ConstructGrid();
//Using Backtracking Solver to fill in a blank grid to get a starting solution - possibly the part of the generator that causes performance issues
bool testing = false;//testing condition
if (!testing)
{
try
{
if (!solve.CompileBacktracker(grid, 2))
{
MessageBox.Show("Generator did not find a puzzle to generate");
}
}
catch (Exception ex)
{
MessageBox.Show("Something has gone terribly wrong...\r\nError: " + ex);
return(grid);
}
}
else
{
#region Manual Testing Puzzle
StringToGrid(grid, "600438079900705080800000032200004060000000000040600003180000005070806001560941008");
#endregion
}
RemoveNumbers(grid, solve);
return(grid);
}
public void RemoveNumbers(SudokuGrid grid, PuzzleSolverAdvDS solve)
{
///This section consists of constantly removing parallel numbers, e.g. [0,0] and [8,8] or [2,5] and [5,2], and checking if the puzzle is still valid (i.e. still has only one solution)
int removed = 0;
List <string> cellsChecked = new List <string>(81);
List <int> rowList = new List <int> {
0, 1, 2, 3, 4, 5, 6, 7, 8
};
List <int> colList = new List <int> {
0, 1, 2, 3, 4, 5, 6, 7, 8
};
rowList = Shuffler_intList(rowList);
colList = Shuffler_intList(colList);
foreach (int row in rowList)
{
if (removed >= g_MaxRemoves)
{
break;
}
foreach (int col in colList)
{
if (removed >= g_MaxRemoves)
{
break;
}
if (!cellsChecked.Contains(row.ToString() + col.ToString()))
{
int altRow = NumberSwitch(row);
int altCol = NumberSwitch(col);
if (grid.Cells[altRow][altCol].Num != '0' && grid.Cells[row][col].Num != '0')
{
bool valid = false;
List <char> numList = new List <char> {
'1', '2', '3', '4', '5', '6', '7', '8', '9'
};
for (int x = 0; x < 9 && !valid; x++)//checks for if the puzzle is valid in the sense that is has more than 7 unique numbers at any point in the puzzle
{
for (int y = 0; y < 9 && !valid; y++)
{
if (grid.Cells[x][y].Num != '0')
{
if ((x == altRow && y == altCol) == false && (x == row && y == col) == false)
{
numList.Remove(grid.Cells[x][y].Num);
}
if (numList.Count <= 1)
{
valid = true;
}
}
}
}
if (valid)
{
char[][] sudokuArray = new char[9][] { new char[9], new char[9], new char[9], new char[9], new char[9], new char[9], new char[9], new char[9], new char[9] };
for (int r = 0; r < 9; r++)
{
for (int c = 0; c < 9; c++)
{
sudokuArray[r][c] = grid.Cells[r][c].Num;
}
}
grid.Cells[row][col].Num = '0';
grid.Cells[altRow][altCol].Num = '0';
if (solve.CompileBacktracker(grid, 4))
{
string firstSol = GridToString(grid);
grid = RestartPuzzle(grid, sudokuArray);
grid.Cells[row][col].Num = '0';
grid.Cells[altRow][altCol].Num = '0';
if (solve.CompileBacktracker(grid, 1))//tries Backtracking algorithm using reversed candidate lists so that if a solution that is different to the previous solution exists, it will be found, invalidating the puzzle
{
string secSol = GridToString(grid);
if (firstSol == secSol)//valid puzzle
{
grid = RestartPuzzle(grid, sudokuArray);
grid.Cells[row][col].Num = '0';
grid.Cells[altRow][altCol].Num = '0';
if (grid.Cells[row][col] == grid.Cells[altRow][altCol])
{
removed++;
}
else
{
removed += 2;
}
}
else//Multiple solutions
{
grid = RestartPuzzle(grid, sudokuArray);
}
}
}
else//Invalid puzzle, should never occur
{
grid = RestartPuzzle(grid, sudokuArray);
}
}
if (grid.Cells[row][col] == grid.Cells[altRow][altCol])
{
cellsChecked.Add(row.ToString() + col.ToString());
}
else
{
cellsChecked.Add(row.ToString() + col.ToString());
cellsChecked.Add(altRow.ToString() + altCol.ToString());
}
}
}
}
}
if (removed < g_MaxRemoves)
{
cellsChecked = new List <string>();
foreach (int row in rowList)
{
if (removed >= g_MaxRemoves)
{
break;
}
foreach (int col in colList)
{
if (removed >= g_MaxRemoves)
{
break;
}
if (!cellsChecked.Contains(row.ToString() + col.ToString()))
{
if (grid.Cells[row][col].Num != '0')
{
bool valid = false;
List <char> numList = new List <char> {
'1', '2', '3', '4', '5', '6', '7', '8', '9'
};
for (int x = 0; x < 9 && !valid; x++)//checks for if the puzzle is valid in the sense that is has more than 7 unique numbers at any point in the puzzle
{
for (int y = 0; y < 9 && !valid; y++)
{
if (grid.Cells[x][y].Num != '0')
{
if ((x == row && y == col) == false)
{
numList.Remove(grid.Cells[x][y].Num);
}
if (numList.Count <= 1)
{
valid = true;
}
}
}
}
if (valid)
{
char[][] sudokuArray = new char[9][] { new char[9], new char[9], new char[9], new char[9], new char[9], new char[9], new char[9], new char[9], new char[9] };
for (int r = 0; r < 9; r++)
{
for (int c = 0; c < 9; c++)
{
sudokuArray[r][c] = grid.Cells[r][c].Num;
}
}
grid.Cells[row][col].Num = '0';
if (solve.CompileBacktracker(grid, 4))
{
string firstSol = GridToString(grid);
grid = RestartPuzzle(grid, sudokuArray);
grid.Cells[row][col].Num = '0';
if (solve.CompileBacktracker(grid, 1))
{
string secSol = GridToString(grid);
if (firstSol == secSol)//valid puzzle
{
grid = RestartPuzzle(grid, sudokuArray);
grid.Cells[row][col].Num = '0';
removed++;
}
else
{
grid = RestartPuzzle(grid, sudokuArray);
}
}
}
else
{
grid = RestartPuzzle(grid, sudokuArray);
}
}
}
cellsChecked.Add(row.ToString() + col.ToString());
}
}
}
}
}