/// <summary>
/// AddLink(row, col) verifies that a cSquare doesn't already exist in the
/// _validationList before adding the cSquare at location _layer[row][col].
/// If the same cSquare was added dupicately, the list would still function,
/// but uncessary duplicate checks would be made:
/// (i.e., is this value = value at _layer[0][1]? OK then, is this value =
/// value at _layer[0][1]? Obviously, The check at [0][1] only needs to be
/// done one time.)
/// </summary>
/// <param name="row"></param>
/// <param name="col"></param>
void AddLink(int row, int col)
{
cSquare sqr = _layer[row][col];
if (!_squareList.Contains(sqr))
{
_squareList.Add(sqr);
}
}
public cRow(int row)
{
_row = row;
_squares = new cSquare[g.PSIZE];
for (int i = 0; i < g.PSIZE; i++)
{
/// square IDs are one-based.
/// Column IDs are passed on zero-based, and adjusted in the
/// cSquare constructor.
_squares[i] = new cSquare(_row, i);
}
}
public bool BuildPuzzle(int seed)
{
cSquare.Seed = seed; // cSquare Seed for Random() is static.
bool success = false;
_cur = new cCurPosition();
cCurPosition lastPosition = new cCurPosition();
int loop = 0;
bool done = false;
while (!done)
{
_cur.SetEqualToMe(lastPosition);
if (_layer[_cur.Row][_cur.Col].TrySetValue())
{
/// be careful not to increment before the EndPostion check as the
/// last cSquare would be missed.
success = done = _cur.EndPosition;
_cur++;
}
else
{
if (_cur.StartPosition)
{
if (_layer[_cur.Row][_cur.Col].AvailableCount() < 1)
{
/// ERROR CONDITION--This would mean that there are no possible
/// sudoku solutions, since we are on the first square of the puzzle,
/// and no more values available to try??
done = true; // what other option is there?
string msg = "cPuzzle.BuildPuzzle()" + Environment.NewLine + "ILLEGAL RESULT: No Solution Found.";
msg += Environment.NewLine + $"1-9 has been exausted at _layer[{_cur.Row}][{_cur.Col}]???";
throw new Exception(msg);
}
} // if (_cur.StartPosition)
else // not _cur.StartPosition...
{
/// no available values for this cell, but we are not at start position, so
/// restore the avialable values for this cell and backspace to try a new value
/// in the previous cell and try again.
bool doneBackspacing = (_layer[_cur.Row][_cur.Col].AvailableCount() > 0);
while (!doneBackspacing)
{
cSquare curSquare = _layer[_cur.Row][_cur.Col];
curSquare.AvailableReset();
int failedValue = curSquare.Value;
curSquare.Value = 0;
/// might be redundant if AvailableCount was 0, but OK....
curSquare.Available[failedValue] = false;
_cur--;
/// ensure that the square we have just backspaced to has values available to
/// try. If it doesn't, back up one more space.
doneBackspacing = _layer[_cur.Row][_cur.Col].AvailableCount() > 0;
}
}
} // else (!_cur.StartPosition)
//if (_cur < lastPosition)
// g.Banner($"Loop: {++loop}: ({_cur.Row}, {_cur.Col}). <<<-- BACKSPACE.");
//else
// g.Banner($"Loop: {++loop}: ({_cur.Row}, {_cur.Col}).");
//Console.WriteLine(_layer);
//g.Pause();
} // while (!done)
return(success);
} // BuildPuzzle
