[LeetCode] Smallest Rectangle Enclosing Black Pixels

 1 class Solution {
 2 public:
 3     int minArea(vector<vector<char>>& image, int x, int y) {
 4         int m = image.size(), n = image[0].size();
 5         int l = search(image,     0, x, 0, n,  true,  true);
 6         int r = search(image, x + 1, m, 0, n, false,  true);
 7         int u = search(image,     0, y, l, r,  true, false);
 8         int d = search(image, y + 1, n, l, r, false, false);
 9         return (r - l) * (d - u);
10     }
11 private:
12     bool white(vector<vector<char>>& image, int mid, int k, int row) {
13         return (row ? image[mid][k] : image[k][mid]) == '0'; 
14     }
15     int search(vector<vector<char>>& image, int b, int e, int mini, int maxi, bool first, bool row) {
16         while (b != e) {
17             int mid = (b + e) / 2, k = mini;
18             while (k < maxi && white(image, mid, k, row)) k++;
19             if (k < maxi == first) e = mid;
20             else b = mid + 1;
21         }
22         return b;
23     }
24 };