1277. Count Square Submatrices with All Ones

class Solution {
    public int countSquares(int[][] matrix) {
        int m = matrix.length;
        if (m == 0) return 0;
        int n = matrix[0].length;
        int res = 0;
        for (int i = 0; i < m; i++) {
            for (int j = 0; j < n; j++) {
                if (matrix[i][j] == 0) continue;
                if (i == 0 || j == 0) {
                    res++;
                    continue;
                }
                int min = Math.min(matrix[i - 1][j],
                                  Math.min(matrix[i][j - 1],
                                          matrix[i - 1][j - 1]));
                matrix[i][j] += min;
                res += matrix[i][j];
            }
        }
        
        return res;
    }
}