Add EKEdge Class to describe a edge’s weight and whether the graph is directed or undirected. At the same time, this class will be used for Prim & Kruskal algorithm.
Add a method to judge if a graph is directed or undirected by its edges
Merge remote-tracking branch 'upstream/master' into Development
Add AVL Tree Structure
Finish AVL Tree data structure with insert and delete operation
Merge pull request #59 from AustinChou/master

Add AVL Tree data structure with insert and delete operation