/// <summary>
/// Finds all zero elements in a NxM matrix and zeroes out their columns and rows
/// O(n) time and space complexity
/// </summary>
/// <param name="inputMatrix">int[,] matrix</param>
/// <returns>int[,] matrix</returns>
public static int[,] ZeroMatrix(int[,] inputMatrix)
{
if (inputMatrix.GetLength(0) == 0 || inputMatrix.GetLength(1) == 0)
{
return(inputMatrix);
}
List <MatrixPointer> zeroList = new List <MatrixPointer>();
for (int row = 0; row < inputMatrix.GetLength(0); row++)
{
for (int col = 0; col < inputMatrix.GetLength(1); col++)
{
if (inputMatrix[row, col] == 0)
{
MatrixPointer zeroPointer = new MatrixPointer(row, col);
zeroList.Add(zeroPointer);
}
}
}
if (zeroList.Count == 0)
{
return(inputMatrix);
}
foreach (MatrixPointer pointer in zeroList)
{
int zeroRow = pointer.Row;
int zeroCol = pointer.Col;
int currRow = 0;
while (currRow < inputMatrix.GetLength(0))
{
if (inputMatrix[currRow, zeroCol] != 0)
{
inputMatrix[currRow, zeroCol] = 0;
}
currRow++;
}
int currCol = 0;
while (currCol < inputMatrix.GetLength(1))
{
if (inputMatrix[zeroRow, currCol] != 0)
{
inputMatrix[zeroRow, currCol] = 0;
}
currCol++;
}
}
return(inputMatrix);
}
private static void SwapPointers(int[,] inputMatrix, MatrixPointer p1, MatrixPointer p2, MatrixPointer p3, MatrixPointer p4)
{
int temp1, temp2;
temp1 = inputMatrix[p2.Row, p2.Col];
inputMatrix[p2.Row, p2.Col] = inputMatrix[p1.Row, p1.Col];
temp2 = temp1;
temp1 = inputMatrix[p3.Row, p3.Col];
inputMatrix[p3.Row, p3.Col] = temp2;
temp2 = temp1;
temp1 = inputMatrix[p4.Row, p4.Col];
inputMatrix[p4.Row, p4.Col] = temp2;
temp2 = temp1;
inputMatrix[p1.Row, p1.Col] = temp1;
}
/// <summary>
/// Rotates matrix in place by 90 degrees.
/// O(n) time complexity, O(n) space
/// </summary>
/// <param name="inputMatrix"></param>
/// <returns></returns>
public static int[,] RotateMatrix(int[,] inputMatrix)
{
Console.WriteLine(inputMatrix.GetLength(0));
if (inputMatrix.Length == 0)
{
return(inputMatrix);
}
int layers = inputMatrix.GetLength(0) / 2;
int min = 0;
int max = inputMatrix.GetLength(0) - 1;
while (layers > 0)
{
MatrixPointer p1 = new MatrixPointer(min, min);
MatrixPointer p2 = new MatrixPointer(min, max);
MatrixPointer p3 = new MatrixPointer(max, max);
MatrixPointer p4 = new MatrixPointer(max, min);
int i = min;
while (i < max)
{
SwapPointers(inputMatrix, p1, p2, p3, p4);
p1.Col++;
p2.Row++;
p3.Col--;
p4.Row--;
i++;
}
min++;
max--;
layers--;
}
return(inputMatrix);
}