Given a non-empty 2D matrix matrix and an integer k, find the max sum of a rectangle in the matrix such that its sum is no larger than k.
Input: matrix = [[1,0,1],[0,-2,3]], k = 2
Explanation: Because the sum of rectangle [[0, 1], [-2, 3]] is 2,
and 2 is the max number no larger than k (k = 2).
The rectangle inside the matrix must have an area > 0.
What if the number of rows is much larger than the number of columns?