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Array/google/SmallestRectangleEnclosingBlackPixels.java

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+public class SmallestRectangleEnclosingBlackPixels {
+    public int minArea(char[][] image, int x, int y) {
+        int top = searchVertical(image, 0, x, true);
+        int bottom = searchVertical(image, x, image.length - 1, false);
+        int left = searchHorizontal(image, 0, y, true);
+        int right = searchHorizontal(image, y, image[0].length - 1, false);
+
+        int area = (bottom - top + 1) * (right - left + 1);
+        return area;
+    }
+
+    public int searchVertical(char[][] image, int top, int bottom, boolean searchTop) {
+        int re = searchTop? bottom: top;
+        while(top <= bottom) {
+            int mid = (top + bottom) / 2;
+            int s = 0;
+            // determine if this horizontal line contains 1 or not
+            for(int j=0; j<image[mid].length; ++j) s += (image[mid][j] - '0');
+            if(s >= 1) {
+                re = mid;
+                if(searchTop) bottom = mid - 1;
+                else top = mid + 1;
+            } else {
+                if(searchTop) top = mid + 1;
+                else bottom = mid - 1;
+            }
+        }
+        return re;
+    }
+
+    public int searchHorizontal(char[][] image, int left, int right, boolean searchLeft) {
+        int re = searchLeft? right: left;
+        while(left <= right) {
+            int mid = (left + right) / 2;
+            int s = 0;
+            for(int i=0; i<image.length; ++i) s += (image[i][mid] - '0');
+            if(s >= 1) {
+                re = mid;
+                if(searchLeft) right = mid - 1;
+                else left = mid + 1;
+            } else {
+                if(searchLeft) left = mid + 1;
+                else right = mid - 1;
+            }
+        }
+        return re;
+    }    
+}