Update README.md

Author: kamyu104

README.md

@@ -1,8 +1,8 @@
-# [LeetCode](https://leetcode.com/problemset/algorithms/) ![Language](https://img.shields.io/badge/language-Python-orange.svg) [![License](https://img.shields.io/badge/license-MIT-blue.svg)](./LICENSE.md) ![Progress](https://img.shields.io/badge/progress-322%20%2F%20322-ff69b4.svg)
+# [LeetCode](https://leetcode.com/problemset/algorithms/) ![Language](https://img.shields.io/badge/language-Python-orange.svg) [![License](https://img.shields.io/badge/license-MIT-blue.svg)](./LICENSE.md) ![Progress](https://img.shields.io/badge/progress-323%20%2F%20323-ff69b4.svg)
 
-Up to date (2015-12-27), there are `305` Algorithms / `13` Database / `4` Shell questions on [LeetCode Online Judge](https://leetcode.com/).
+Up to date (2015-12-29), there are `306` Algorithms / `13` Database / `4` Shell questions on [LeetCode Online Judge](https://leetcode.com/).
 The number of questions is increasing recently.
-Here is the classification of all `322` questions.
+Here is the classification of all `323` questions.
 For more questions and solutions, you can see my [LintCode](https://github.com/kamyu104/LintCode) repository.
 I'll keep updating for full summary and better solutions. Stay tuned for updates.
 (Notes: "📖" means you need to subscribe to [LeetCode premium membership](https://leetcode.com/subscribe/) for the access to premium questions. )
@@ -208,6 +208,7 @@ I'll keep updating for full summary and better solutions. Stay tuned for updates
 299| [Bulls and Cow](https://leetcode.com/problems/bulls-and-cow/) | [C++](./C++/bulls-and-cow.cpp) [Python](./Python/bulls-and-cow.py)  | _O(n)_ | _O(1)_ | Easy         |||
 305| [Number of Islands II](https://leetcode.com/problems/number-of-islands-ii/) | [C++](./C++/number-of-islands-ii.cpp) [Python](./Python/number-of-islands-ii.py) | _O(k)_ | _O(k)_| Hard         | LintCode, 📖 | Union Find
 314| [Binary Tree Vertical Order Traversal](https://leetcode.com/problems/binary-tree-vertical-order-traversal/) | [C++](./C++/binary-tree-vertical-order-traversal.cpp) [Python](./Python/binary-tree-vertical-order-traversal.py) | _O(n)_ | _O(n)_| Medium         | 📖 | BFS
+323| [Number of Connected Components in an Undirected Graph](https://leetcode.com/problems/number-of-connected-components-in-an-undirected-graph/) | [C++](./C++/number-of-connected-components-in-an-undirected-graph.cpp) [Python](./Python/number-of-connected-components-in-an-undirected-graph.py) | _O(n)_ | _O(n)_| Medium         | 📖 | Union Find
 
 ## Data Structure
   #  | Problem         |  Solution       |  Time           | Space           | Difficulty    | Tag          | Note