1 public static void matrixZero(int[][] matrix) { 2     if (matrix.length == 0 || matrix[0].length == 0) 3         return; 4  5     int m = matrix.length; 6     int n = matrix[0].length; 7     boolean rowZero = false; 8     boolean colZero = false; 9 10     // save first row and first col11     for (int i = 0; i < m; i++)12         if (matrix[i][0] == 0)13             rowZero = true;14     for (int i = 0; i < n; i++)15         if (matrix[0][i] == 0)16             colZero = true;17 18     for (int i = 0; i < m; i++) {19         for (int j = 0; j < n; j++) {20             if (matrix[i][j] == 0) {21                 matrix[i][0] = 0;22                 matrix[0][j] = 0;23             }24         }25     }26 27     for (int i = 1; i < m; i++) {28         if (matrix[i][0] == 0)29             for (int j = 1; j < n; j++) {30                 matrix[i][j] = 0;31             }32     }33 34     for (int i = 1; i < n; i++) {35         if (matrix[0][i] == 0)36             for (int j = 1; j < m; j++) {37                 matrix[j][i] = 0;38             }39     }40 41     if (rowZero) {42         for (int i = 0; i < m; i++)43             matrix[i][0] = 0;44     }45 46     if (colZero) {47         for (int i = 0; i < n; i++)48             matrix[0][i] = 0;49     }50 }