Add example of simple graph algorithms

+ Using pseudocode examples from MIT Intro to Algorithms

cpp/algorithms/graphs/simple/lib-graph.hpp

@@ -0,0 +1,36 @@
+/*#############################################################################
+## Author: Shaun Reed                                                        ##
+## Legal: All Content (c) 2021 Shaun Reed, all rights reserved               ##
+## About: An example of a simple graph implementation                        ##
+##        Algorithms in this example are found in MIT Intro to Algorithms    ##
+##                                                                           ##
+## Contact: shaunrd0@gmail.com  | URL: www.shaunreed.com | GitHub: shaunrd0  ##
+###############################################################################
+*/
+#ifndef LIB_GRAPH_HPP
+#define LIB_GRAPH_HPP
+
+#include <iostream>
+#include <map>
+#include <queue>
+#include <set>
+#include <vector>
+
+
+class Graph {
+public:
+  explicit Graph(std::map<int, std::set<int>> nodes) : nodes_(std::move(nodes)) {}
+  std::map<int, std::set<int>> nodes_;
+
+  void BFS(int startNode);
+
+  void DFS();
+  void DFSVisit(int startNode, std::vector<bool> &discovered);
+
+  std::vector<int> TopologicalSort();
+  void TopologicalVisit(
+      int startNode, std::vector<bool> &discovered, std::vector<int> &order
+  );
+};
+
+#endif // LIB_GRAPH_HPP