leetcode

0 class Solution {

1 public:

2 int numSubmat(vector<vector<int>> &mat) const {

3 const int n = size(mat), m = size(mat[0]);

4

5 for (int j = 0; j < m; j++) {

6 for (int i = 0, acc = 0; i < n; i++) {

7 if (mat[i][j])

8 mat[i][j] = acc += 1;

9 else

10 acc = 0;

11 }

12 }

13

14 int res = 0;

15 for (int i = 0; i < n; i++) {

16 for (int j = 0; j < m; j++) {

17 int mini = mat[i][j];

18 for (int k = j; k >= 0; k--) {

19 mini = min(mini, mat[i][k]);

20 if (!mini) break;

21 res += mini;

22 }

23 }

24 }

25 return res;

26 }

27 };