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.

Example:

1 2 3 4

Input: matrix = [[1,0,1],[0,-2,3]], k = 2 Output: 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).

Note:

The rectangle inside the matrix must have an area > 0.

What if the number of rows is much larger than the number of columns?

classSolution { public: intmaxSumSubmatrix(std::vector<std::vector<int>>& matrix, int k){ int row = matrix.size(); if(row == 0) { return0; } int col = matrix[0].size(); int res = INT_MIN;

for(int i = 0; i < col; i++) { auto sum = std::vector<int>(row, 0); for(int j = i; j < col; j++) { for(int z = 0; z < row; z++) { sum[z] += matrix[z][j]; }

autoset = std::set<int>(); set.insert(0); int currentSum = 0; for(int num : sum) { currentSum += num; auto it = set.lower_bound(currentSum - k); if(it != set.end()) { res = std::max(res, currentSum - *it); } set.insert(currentSum); } } } return res; } };