/// <summary>
/// Convert the puzzle grid to string
/// </summary>
/// <param name="puzzleGrid"></param>
/// <returns>Grid</returns>
string PuzzleGrid(Cell[,] puzzleGrid)
{
StringBuilder puzzle = new StringBuilder();
for (int row = 0; row < 9; row++)
for (int column = 0; column < 9; column++)
if (string.IsNullOrEmpty(puzzleGrid[row, column].Digit))
puzzle.Append("0");
else
puzzle.Append(puzzleGrid[row, column].Digit);
return puzzle.ToString();
}
/// <summary>
/// Remove the current cell
/// </summary>
/// <param name="currentCell"></param>
public void Dig(Cell currentCell)
{
string digit = currentCell.Digit;
currentCell.Digit = string.Empty;
currentCell.IsGiven = false;
if (!IterateGrid())
{
currentCell.IsGiven = true;
currentCell.Digit = digit;
}
CleanGrid();
}
/// <summary>
/// Get the digits valid for the current cell
/// </summary>
/// <param name="currentCell"></param>
/// <returns>Valid digits</returns>
string ValidDigits(Cell currentCell)
{
string startSequence = Utility.START_SEQUENCE;
if (currentCell.RestrictedDigits.Length < 9)
{
for (int i = 0; i < currentCell.RestrictedDigits.Length; i++)
currentCell.ValidDigits = startSequence = startSequence.Replace(currentCell.RestrictedDigits.Substring(i, 1), string.Empty);
return currentCell.ValidDigits;
}
else
return currentCell.ValidDigits = string.Empty;
}
/// <summary>
/// Validate if the current cell fits in the pattern
/// </summary>
/// <param name="currentCell"></param>
/// <returns>True if the pattern is valid</returns>
bool ValidatePattern(Cell currentCell)
{
if (!string.IsNullOrEmpty(this.Last.Digit))
return true;
if (ValidateCell(currentCell))
{
while (currentCell.ValidDigits.Length > 0)
{
currentCell.Digit = currentCell.ValidDigits.Substring(r.Next(currentCell.ValidDigits.Length), 1);
currentCell.ValidDigits = currentCell.ValidDigits.Replace(currentCell.Digit, string.Empty);
if (ValidatePattern(GetCell(currentCell)))
return true;
}
}
currentCell.RestrictedDigits = currentCell.Digit;
currentCell.Digit = string.Empty;
currentCell.ValidDigits = Utility.START_SEQUENCE;
if (string.IsNullOrEmpty(Last.Digit))
this.PreviousCell(currentCell).Digit = string.Empty;
return false;
}
/// <summary>
/// Validate if the current cell value fits the pattern
/// </summary>
/// <param name="currentCell"></param>
/// <returns>True if the cell fits</returns>
bool ValidateCell(Cell currentCell)
{
if (RestrictedDigits(currentCell).Length == 9)
return false;
ValidDigits(currentCell);
return true;
}
/// <summary>
/// Get the digits not allowed in the current cell
/// </summary>
/// <param name="currentCell"></param>
/// <returns>Invalid digits</returns>
string RestrictedDigits(Cell currentCell)
{
int row = currentCell.Index.Row;
int column = currentCell.Index.Column;
StringBuilder combination = new StringBuilder();
for (int i = 0; i < 9; i++)
{
if (combination.ToString().IndexOf(this.Puzzle[row, i].Digit) == -1)
combination.Append(this.Puzzle[row, i].Digit);
if (combination.ToString().IndexOf(this.Puzzle[i, column].Digit) == -1)
combination.Append(this.Puzzle[i, column].Digit);
if (i == column)
{
if (combination.ToString().IndexOf(this.Puzzle[row + CUBE_LOOKUP[row % 3], i + CUBE_LOOKUP[i % 3]].Digit) == -1)
combination.Append(this.Puzzle[row + CUBE_LOOKUP[row % 3], i + CUBE_LOOKUP[i % 3]].Digit);
if (combination.ToString().IndexOf(this.Puzzle[row + CUBE_LOOKUP[(row % 3) + 3], i + CUBE_LOOKUP[i % 3]].Digit) == -1)
combination.Append(this.Puzzle[row + CUBE_LOOKUP[(row % 3) + 3], i + CUBE_LOOKUP[i % 3]].Digit);
}
if (i == row)
{
if (combination.ToString().IndexOf(this.Puzzle[i + CUBE_LOOKUP[i % 3], column + CUBE_LOOKUP[(column % 3) + 3]].Digit) == -1)
combination.Append(this.Puzzle[i + CUBE_LOOKUP[i % 3], column + CUBE_LOOKUP[(column % 3) + 3]].Digit);
if (combination.ToString().IndexOf(this.Puzzle[i + CUBE_LOOKUP[(i % 3) + 3], column + CUBE_LOOKUP[(column % 3) + 3]].Digit) == -1)
combination.Append(this.Puzzle[i + CUBE_LOOKUP[(i % 3) + 3], column + CUBE_LOOKUP[(column % 3) + 3]].Digit);
}
}
return currentCell.RestrictedDigits = combination.ToString();
}
/// <summary>
/// Create easy puzzle
/// </summary>
/// <param name="currentCell"></param>
void GenerateEasyGrid(Cell currentCell)
{
string digit;
currentCell.IsGiven = true;
digit = currentCell.Digit;
currentCell.RestrictedDigits = RestrictedDigits(currentCell);
if (currentCell.RestrictedDigits.Length == 9)
{
currentCell.Digit = string.Empty;
currentCell.IsGiven = false;
}
}
/// <summary>
/// Get the cell previous to the current cell
/// </summary>
/// <param name="currentCell"></param>
/// <returns>Cell</returns>
public Cell PreviousCell(Cell currentCell)
{
int row = currentCell.Index.Row;
int column = currentCell.Index.Column;
if (column > 0)
return this.Puzzle[row, column - 1];
else
return this.Puzzle[row - 1, 8];
}
/// <summary>
/// Get the next cell to the current cell
/// </summary>
/// <param name="currentCell"></param>
/// <returns>Cell</returns>
public Cell NextCell(Cell currentCell)
{
int row = currentCell.Index.Row;
int column = currentCell.Index.Column;
if (column == 8)
return this.Puzzle[row + 1, 0];
else
return this.Puzzle[row, column + 1];
}
/// <summary>
/// Get the next empty cell
/// </summary>
/// <param name="currentCell"></param>
/// <returns>Cell</returns>
public Cell GetCell(Cell currentCell)
{
int row = currentCell.Index.Row;
int column = currentCell.Index.Column;
if (row == 0 && column == 0)
return this.Puzzle[row, column + 1];
if (row == 8 && column == 8)
return this.Last;
Cell previousCell = PreviousCell(currentCell);
if (string.IsNullOrEmpty(previousCell.Digit))
return previousCell;
else if (string.IsNullOrEmpty(currentCell.Digit))
return currentCell;
else
return NextCell(currentCell);
}
/// <summary>
/// Generate the terminal pattern
/// </summary>
/// <param name="terminalPattern"></param>
/// <returns>Solution</returns>
string TerminalPattern(Cell[,] terminalPattern)
{
StringBuilder solution = new StringBuilder();
for (int row = 0; row < 9; row++)
{
for (int column = 0; column < 9; column++)
{
solution.Append(terminalPattern[row, column].Digit);
}
}
return solution.ToString();
}