/* Solver */
/// <summary>
/// The SuDoku Solver's algorithm only uses logical arguments to solve the puzzles.
/// It does not use 'trial and error' methods. For anybody interested in an explanation
/// of the algorithm it employs to solve your SuDoku then please read on. The Solver
/// stores two grids (as arrays), one is the actual SuDoku grid itself, and the second
/// contains all the 'possible values' for each square. Initially all values (1-9) would
/// be possible for all squares of course. The algorithm then tries a number of steps to
/// solve the puzzle, stopping when it either solves the SuDoku or all the following steps
/// fail to find any new values.
/// </summary>
public bool SolveBoard()
{
// Initialize fields
possibleValues = new List <int> [_board.GetBoardSize(), _board.GetBoardSize()];
// Create a list of all possible values
for (int i = 0; i < _board.GetBoardSize(); i++)
{
for (int j = 0; j < _board.GetBoardSize(); j++)
{
if (_board.IsNumberBlank(i, j))
{
possibleValues[i, j] = new List <int>().GenerateAllPossibleValues(_board.GetBoardSize());
}
else
{
possibleValues[i, j] = new List <int>();
}
}
}
// Find new numbers until the board is solved
while (true)
{
// Perform step 1, noting any new numbers
int foundNumbers = SolverStep1();
if (Validator.ValidateBoard(_board, true))
{
return(true);
}
// Perform step 2, noting any new numbers
foundNumbers += SolverStep2();
if (Validator.ValidateBoard(_board, true))
{
return(true);
}
// If neither of step 1 nor 2 finds a number, move to step 3 and 4
if (foundNumbers == 0)
{
// Perform step 3, noting any changes to possible values
bool foundInvalidValues = SolverStep3();
// Perform step 4, noting any changes to possible values
foundInvalidValues |= SolverStep4();
// If no new information is found, try brute force
if (!foundInvalidValues)
{
return(BruteForce());
}
}
}
}
/* Parsers */
public static string ParseDataFromBoard(AbstractBoard board)
{
StringBuilder text = new StringBuilder();
for (int i = 0; i != board.GetBoardSize(); i++)
{
// Add newline separators after the first line
if (i > 0)
{
text.Append(Environment.NewLine);
}
for (int j = 0; j != board.GetBoardSize(); j++)
{
// Add comma separators after the first number
if (j > 0)
{
text.Append(",");
}
// Add non-blank numbers
if (!board.IsNumberBlank(i, j))
{
text.Append(board.GetNumber(i, j));
text.Append(board.IsNumberPredefined(i, j) ? "T" : "F");
}
}
}
return(text.ToString());
}
/* Parsers */
public static string ParseDataFromBoard(AbstractBoard board)
{
StringBuilder text = new StringBuilder();
for (int i = 0; i != board.GetBoardSize(); i++)
{
// Add newline separators after the first line
if (i > 0)
text.Append(Environment.NewLine);
for (int j = 0; j != board.GetBoardSize(); j++)
{
// Add comma separators after the first number
if (j > 0)
text.Append(",");
// Add non-blank numbers
if (!board.IsNumberBlank(i, j))
{
text.Append(board.GetNumber(i, j));
text.Append(board.IsNumberPredefined(i, j) ? "T" : "F");
}
}
}
return text.ToString();
}
public static bool ValidateSection(AbstractBoard board, IEnumerable<Coordinate> cells, bool completeCheck = false)
{
HashSet<int> previousValues = new HashSet<int>();
foreach (Coordinate cell in cells)
{
// Get current value
int value = board.GetNumber(cell.Row, cell.Column);
// Check if the current value is blank
if (board.IsNumberBlank(cell.Row, cell.Column))
{
// For a complete check; none of the numbers are allowed to be blank
// Otherwise skip to next cell
if (completeCheck)
return false;
else
continue;
}
// Check if the current value is duplicated
if (previousValues.Contains(value))
return false;
// Store the current value
previousValues.Add(value);
}
// No duplicates
return true;
}
public bool IsNumberBlank(int row, int column)
{
if (_board != null)
{
return(_board.IsNumberBlank(row, column));
}
else
{
throw new GameNotStartedException();
}
}
private void RemoveNumbersInCell(int CellsToClear) // clear cells
{
int j = 0;
do
{
int randomRow = RandomNumberGen(0, _board.GetBoardSize());
int randomColumn = RandomNumberGen(0, _board.GetBoardSize());
if (!_board.IsNumberBlank(randomRow, randomColumn))
{
_board.ClearNumber(randomRow, randomColumn);
j++;
}
} while (j < CellsToClear);
}
public static bool ValidateSection(AbstractBoard board, IEnumerable <Coordinate> cells, bool completeCheck = false)
{
HashSet <int> previousValues = new HashSet <int>();
foreach (Coordinate cell in cells)
{
// Get current value
int value = board.GetNumber(cell.Row, cell.Column);
// Check if the current value is blank
if (board.IsNumberBlank(cell.Row, cell.Column))
{
// For a complete check; none of the numbers are allowed to be blank
// Otherwise skip to next cell
if (completeCheck)
{
return(false);
}
else
{
continue;
}
}
// Check if the current value is duplicated
if (previousValues.Contains(value))
{
return(false);
}
// Store the current value
previousValues.Add(value);
}
// No duplicates
return(true);
}
