Update Graph Theory resources in README

Author: ashishps1

README.md

@@ -32,8 +32,8 @@ This repository contains awesome LeetCode resources to learn Data Structures and
 - [Binary Search](https://leetcode.com/discuss/study-guide/786126/Python-Powerful-Ultimate-Binary-Search-Template.-Solved-many-problems)
 - [Greedy Algorithm](https://www.freecodecamp.org/news/greedy-algorithms/)
 - [Dynamic Programming](https://medium.com/basecs/less-repetition-more-dynamic-programming-43d29830a630)
-- [Graph Theory](https://medium.com/basecs/a-gentle-introduction-to-graph-theory-77969829ead8)
-- [Important Graph Algorithms](https://blog.algomaster.io/p/master-graph-algorithms-for-coding)
+- [Graph Theory](https://www.youtube.com/watch?v=xN5VGzK9_FQ&list=PLK63NuByH5o9odyBT7nfYkHZyvGQ5oVp2)
+- [Master Graph Algorithms](https://blog.algomaster.io/p/master-graph-algorithms-for-coding)
 - [DFS Traversal](https://medium.com/basecs/deep-dive-through-a-graph-dfs-traversal-8177df5d0f13)
 - [BFS Traversal](https://medium.com/basecs/going-broad-in-a-graph-bfs-traversal-959bd1a09255)
 - [Union-Find](https://leetcode.com/discuss/general-discussion/1072418/Disjoint-Set-Union-(DSU)Union-Find-A-Complete-Guide)