updating DIRECTORY.md

Author: github-actions

Diff for: DIRECTORY.md

@@ -341,6 +341,7 @@
   * [Longest Increasing Subsequence O(Nlogn)](dynamic_programming/longest_increasing_subsequence_o(nlogn).py)
   * [Longest Palindromic Subsequence](dynamic_programming/longest_palindromic_subsequence.py)
   * [Longest Sub Array](dynamic_programming/longest_sub_array.py)
+  * [Matrix Chain Multiplication](dynamic_programming/matrix_chain_multiplication.py)
   * [Matrix Chain Order](dynamic_programming/matrix_chain_order.py)
   * [Max Non Adjacent Sum](dynamic_programming/max_non_adjacent_sum.py)
   * [Max Product Subarray](dynamic_programming/max_product_subarray.py)