private static void FillMatrix(int[,] matrix, Cell startupCell)
{
var currentCell = startupCell;
var dirIndex = 0;
while (IsCellPassable(matrix, currentCell))
{
matrix[currentCell.X, currentCell.Y] = currentCell.Value;
while (!IsNextCellPassable(matrix, currentCell, dirIndex) &&
CanCellMoveSomewhere(matrix, currentCell, dirIndex))
{
dirIndex = (dirIndex + 1) % dirX.Length;
}
// Faster and low-memory instead creating new object
currentCell.X += dirX[dirIndex];
currentCell.Y += dirY[dirIndex];
currentCell.Value++;
}
// Calls FillMatrix recursively with next empty passable cell if exists
var nextStartupCell = FindFirstEmptyCellIfExists(matrix);
if (nextStartupCell != null)
{
nextStartupCell.Value = currentCell.Value;
FillMatrix(matrix, nextStartupCell);
}
}
private static bool IsCellPassable(int[,] matrix, Cell currentCell)
{
bool isCellPassable = currentCell.X >= 0 && currentCell.X < matrix.GetLongLength(0) &&
currentCell.Y >= 0 && currentCell.Y < matrix.GetLongLength(1) &&
matrix[currentCell.X, currentCell.Y] == 0;
return isCellPassable;
}
private static bool IsNextCellPassable(int[,] matrix, Cell currentCell, int dirIndex)
{
Cell nextCell = new Cell()
{
X = currentCell.X + dirX[dirIndex],
Y = currentCell.Y + dirY[dirIndex]
};
return IsCellPassable(matrix, nextCell);
}
private static Cell FindFirstEmptyCellIfExists(int[,] matrix)
{
for (int i = 0; i < matrix.GetLength(0); i++)
{
for (int j = 0; j < matrix.GetLength(0); j++)
{
if (matrix[i, j] == 0)
{
var firstEmptyCell = new Cell(i, j);
return firstEmptyCell;
}
}
}
return null;
}
private static bool CanCellMoveSomewhere(int[,] matrix, Cell currentCell, int dirIndex)
{
for (int i = 0; i < dirX.Length; i++)
{
dirIndex = (dirIndex + 1) % dirX.Length;
if (IsNextCellPassable(matrix, currentCell, dirIndex))
{
return true;
}
}
return false;
}
