Add different graph algorithms

[magesoe]

Kruskal, Dijktra, Prim, Hungarian and so on...

[ericdrowell]

Open to adding more algos. Please create a PR for this.

[murraycu]

By the way, Dijkstra's (SSSP) and Prim's (MST) (but not Kruskal's MST) are there now. The Hungarian Algorithm is not there.