221. Maximal Square

 1     public int maximalSquare(char[][] matrix) {
 2         if(matrix.length == 0 || matrix[0].length == 0) {
 3             return 0;
 4         }
 5         int row = matrix.length;
 6         int col = matrix[0].length;
 7         int max = 0;
 8         int[][] res = new int[row][col];
 9         for(int i = 0; i < row; i++) {
10             res[i][0] = (matrix[i][0] == ‘1‘)? 1:0;
11             if(res[i][0] > 0) {
12                 max = 1;
13             }
14         }
15         for(int i = 0; i< col; i++) {
16             res[0][i] = (matrix[0][i] == ‘1‘)? 1:0;
17             if(res[0][i] > 0) {
18                 max = 1;
19             }
20         }
21         for(int i = 1; i < row; i++) {
22             for(int j = 1; j < col; j++) {
23                 if(matrix[i][j] == ‘1‘) {
24                     res[i][j] = Math.min(Math.min(res[i-1][j], res[i-1][j-1]), res[i][j-1]) + 1;
25                     if(res[i][j] > max) {
26                         max = res[i][j];
27                     }
28                 }
29             }
30         }
31         return max * max;
32     }