/// <summary>
/// Finds the maximum sum rectangle with contiguous elements except the given element.
/// </summary>
/// <param name="a">Input array.</param>
/// <param name="elementToExclude">The element to exclude.</param>
/// <returns>
/// Rectangle object
/// (contains the indexes marking top-left, top-right, bottom-left, bottom-right corners of the rectangle) if the max sum rectangle found;
/// Null otherwise.
/// Note: This method will ignore the rectangle row/column if it contains the element that was asked to exclude.
/// </returns>
/// <remarks>This method will ignore the rectangle row/column if it contains the element that was asked to exclude.</remarks>
/// <seealso cref="ArrayOperations.FindMaxSumSubArrayByKadanesAlgorithmCustom(int[], int)"/>
public static Rectangle FindMaxSumRectangleWithContiguousElementsExcept(int[,] a, int elementToExclude)
{
int cols = a.GetLength(1),
rows = a.GetLength(0);
bool rectangleFound = false;
Rectangle result = new Rectangle();
for (int leftPointer = 0; leftPointer < cols; leftPointer++)
{
int[] colSumArray = new int[rows];
bool[] AreZerosExistsInRow = new bool[rows];
for (int rightPointer = leftPointer; rightPointer < cols; rightPointer++)
{
for (int i = 0; i < rows; i++)
{
if (a[i, rightPointer] == elementToExclude)
{
AreZerosExistsInRow[i] = true;
// if the total till previous column is > 0.. but we have azero in the current row/column. Hence ignore the previous total.
colSumArray[i] = 0;
}
else if (!AreZerosExistsInRow[i])
{
colSumArray[i] += a[i, rightPointer];
}
}
var maxSumSubArray = ArrayOperations.FindMaxSumSubArrayByKadanesAlgorithmCustom(colSumArray, elementToExclude);
if (maxSumSubArray.Sum > result.Sum)
{
result.Sum = maxSumSubArray.Sum;
result.ColumnStartIndex = leftPointer;
result.ColumnEndIndex = rightPointer;
result.RowStartIndex = maxSumSubArray.SubArrayIndexes[0].Item1;
result.RowEndIndex = maxSumSubArray.SubArrayIndexes[0].Item2;
rectangleFound = true;
}
}
}
if (rectangleFound)
{
return(result);
}
else
{
return(null);
}
}
/// <summary>
/// Finds the maximum sum rectangle.
/// </summary>
/// <param name="a">Input array.</param>
/// <returns>Rectangle object
/// (contains the indexes marking top-left, top-right, bottom-left, bottom-right corners of the rectangle) if the max sum rectangle found;
/// Null otherwise.
/// </returns>
/// <seealso cref="ArrayOperations.FindMaxSumSubArrayByKadanesAlgorithm(int[])"/>
public static Rectangle FindMaxSumRectangle(int[,] a)
{
int cols = a.GetLength(1),
rows = a.GetLength(0);
bool rectangleFound = false;
Rectangle result = new Rectangle();
for (int leftPointer = 0; leftPointer < cols; leftPointer++)
{
/* reset the array that stores the sum of elements in the rows
* (and presents columns from left pointer to right pointer)
* */
int[] colSumArray = new int[rows];
for (int rightPointer = leftPointer; rightPointer < cols; rightPointer++)
{
for (int i = 0; i < rows; i++)
{
colSumArray[i] += a[i, rightPointer];
}
var maxSumSubArray = default(SubArraySumResult);
maxSumSubArray = ArrayOperations.FindMaxSumSubArrayByKadanesAlgorithm(colSumArray);
if (maxSumSubArray.Sum > result.Sum)
{
result.Sum = maxSumSubArray.Sum;
result.ColumnStartIndex = leftPointer;
result.ColumnEndIndex = rightPointer;
result.RowStartIndex = maxSumSubArray.SubArrayIndexes[0].Item1;
result.RowEndIndex = maxSumSubArray.SubArrayIndexes[0].Item2;
rectangleFound = true;
}
}
}
if (rectangleFound)
{
return(result);
}
else
{
return(null);
}
}
