302. Smallest Rectangle Enclosing Black Pixels My Submissions QuestionEditorial Solution

An image is represented by a binary matrix with 0 as a white pixel and 1 as a black pixel. The black pixels are connected, i.e., there is only one black region. Pixels are connected horizontally and vertically. Given the location (x, y) of one of the black pixels, return the area of the smallest (axis-aligned) rectangle that encloses all black pixels.

For example, given the following image:

[
  "0010",
  "0110",
  "0100"
]

and x = 0, y = 2, return 6.

 1 public class Solution {
 2     public int minArea(char[][] image, int x, int y) {
 3         int m = image.length;
 4         int n = image[0].length;
 5
 6         int left = bsHor(image, 0, y, 0, m, true);
 7         int right = bsHor(image, y+1, n, 0, m, false);
 8         int top = bsVer(image, 0, x, left, right, true);
 9         int bottom = bsVer(image, x+1, m, left, right, false);
10
11         return (bottom - top) * (right - left);
12     }
13
14     private int bsHor(char[][] image, int i, int j, int top, int bottom, boolean leftSide) {
15         while (i != j) {
16             int k = top;
17             int mid = (j - i) / 2 + i;
18             while (k<bottom && image[k][mid] == ‘0‘) k++;
19             if (k < bottom == leftSide) {
20                 j = mid;
21             } else {
22                 i = mid + 1;
23             }
24         }
25         return i;
26     }
27
28     private int bsVer(char[][] image, int i, int j, int left, int right, boolean upSide) {
29         while (i != j) {
30             int k = left;
31             int mid = (j - i) / 2 + i;
32             while (k<right && image[mid][k] == ‘0‘) k++;
33             if (k < right == upSide) {
34                 j = mid;
35             } else {
36                 i = mid + 1;
37             }
38         }
39         return i;
40     }
41 }