Update README.md

Author: kamyu104

README.md

@@ -170,7 +170,7 @@ Shell
   #  | Problem         |  Solution       |  Time           | Space           | Difficulty    | Tag          | Note
 -----|---------------- | --------------- | --------------- | --------------- | ------------- |--------------| -----
 23| [Merge k Sorted Lists](https://leetcode.com/problems/merge-k-sorted-lists/) | [Python](./Python/merge-k-sorted-lists.py) | _O(nlogk)_| _O(k)_| Hard          ||
-264| [Ugly Number II](https://leetcode.com/problems/ugly-number-ii/) | [C++](./C++/ugly-number-ii.cpp)  [Python](./Python/ugly-number-ii.py)  | _O(n)_ | _O(1)_ | Medium         |||
+264| [Ugly Number II](https://leetcode.com/problems/ugly-number-ii/) | [C++](./C++/ugly-number-ii.cpp)  [Python](./Python/ugly-number-ii.py)  | _O(n)_ | _O(1)_ | Medium         | CTCI, LintCode | BST, Heap |
 
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