Update smallest-rectangle-enclosing-black-pixels.cpp

Author: kamyu104

C++/smallest-rectangle-enclosing-black-pixels.cpp

@@ -1,11 +1,52 @@
 // Time:  O(nlogn)
 // Space: O(1)
 
+// Using template.
 class Solution {
 public:
     int minArea(vector<vector<char>>& image, int x, int y) {
         using namespace std::placeholders;  // for _1, _2, _3...
 
+        const auto searchColumns =
+            [](const vector<vector<char>>& image, bool has_one, const int mid) {
+                return has_one == any_of(image.cbegin(), image.cend(),
+                                         [=](const vector<char>& row) { return row[mid] == '1'; });
+            };
+        const auto searchRows =
+            [](const vector<vector<char>>& image, bool has_one, const int mid) {
+                return has_one == any_of(image[mid].cbegin(), image[mid].cend(),
+                                         [](const char& col) { return col == '1'; });
+            };
+
+        const int left = binarySearch(0, y - 1, bind(searchColumns, image, true, _1));
+        const int right = binarySearch(y + 1, image[0].size() - 1, bind(searchColumns, image, false, _1));
+        const int top = binarySearch(0, x - 1, bind(searchRows, image, true, _1));
+        const int bottom = binarySearch(x + 1, image.size() - 1, bind(searchRows, image, false, _1));
+
+        return (right - left) * (bottom - top);
+    }
+    
+private:
+    template<typename T>
+    int binarySearch(int left, int right, const T& find) {
+        while (left <= right) {
+            const int mid = left + (right - left) / 2;
+            if (find(mid)) {
+                right = mid - 1;
+            } else {
+                left = mid + 1;
+            }
+        }
+        return left;
+    }
+};
+
+// Using std::bind().
+class Solution2 {
+public:
+    int minArea(vector<vector<char>>& image, int x, int y) {
+        using namespace std::placeholders;  // for _1, _2, _3...
+
         const auto searchColumns =
             [](const vector<vector<char>>& image, bool has_one, const int mid) {
                 return has_one == any_of(image.cbegin(), image.cend(),
@@ -46,8 +87,8 @@ class Solution {
     }
 };
 
-
-class Solution2 {
+// Using lambda.
+class Solution3 {
 public:
     int minArea(vector<vector<char>>& image, int x, int y) {
         const auto searchColumns =