Update README for problem 115

Author: anirudhology

Diff for: README.md

@@ -56,6 +56,7 @@ LeetCode solutions in Python
 | 104        | Maximum Depth Of Binary Tree                              | [Solution](problems/tree/maximum_depth_of_binary_tree.py)                                  | Easy       | Binary Tree, Recursion                |
 | 105        | Construct Binary Tree From Preorder And Inorder Traversal | [Solution](problems/tree/construct_binary_tree_from_preorder_and_inorder_traversal.py)     | Medium     | Binary Tree, DFS                      |
 | 110        | Balanced Binary Tree                                      | [Solution](problems/tree/balanced_binary_tree.py)                                          | Easy       | Binary Tree, DFS                      |
+| 115        | Distinct Subsequences                                     | [Solution](problems/dynamic_programming/distinct_subsequences.py)                          | Hard       | Dynamic Programming                   |
 | 121        | Best Time To Buy And Sell Stocks                          | [Solution](problems/sliding_window/best_time_to_buy_and_sell_stocks.py)                    | Easy       | Sliding Window                        |
 | 124        | Binary Tree Maximum Path Sum                              | [Solution](problems/tree/binary_tree_maximum_path_sum.py)                                  | Hard       | Binary Tree, DFS                      |
 | 125        | Valid Palindrome                                          | [Solution](problems/string/valid_palindrome.py)                                            | Medium     | String, Two Pointers                  |