Alternate swappin. it's not working for odd lenth

#1
#2

You code implementation is wrong and i am not able to understand your logic.
But you can do this in o(n^2)
For each element of the matrix, we try to find the number of sub-matrices, the element will lie in.

This can be done in O(1) time. Let us suppose the index of an element be (X, Y) in 0 based indexing, then the number of submatrices (Sx, y) for this element will be in can be given by the formula S(x, y) = (X + 1) * (Y + 1) * (N – X) * (N – Y) . This formula works, because we just have to choose two different positions on the matrix that will create a submatrix that envelopes the element. Thus, for each element, ‘sum’ can be updated as sum += (S(x, y)) * Arr(x, y) .

This is the implementation

int sum = 0;
for (int i = 0; i < n; i++)
{
	for (int j = 0; j < n; j++)
	{
		int top = (i + 1) * (j + 1);  // ways to choose from top-left elements
		int bottom = (n - i) * (n - j); // ways to choose from bottom-right elements 
		sum += (top * bottom * arr[i][j]);
	}
}
return sum;
#3

i asked regarding alternate swapping of array element
for example 12345 will give output 21435

#4

If question is this Alternate swappin then why you put it in Sum Of All Submatrix From A given Matrix the content.
But its ok.
First see this how i debug the code bu cout statement. See in the code
Then the correct code is in comment

#5

still it’s not giving correct output

#6

On which test case ?