Make class Graph abstract and make derived classes Digraph and SCC

algorithm/bfs.h

@@ -1,18 +1,18 @@
 #ifndef BFS_H_
 #define BFS_H_
 
-#include "graph/graph.h"
-using namespace graph;
+#include "graph/digraph.h"
 
-#include <algorithm>
 #include <queue>
 
+using namespace graph;
+
 namespace algo {
 
 template<typename T>
 class BFS {
 public:
-  BFS(Graph<T> G, T root) : G(G), root(root) {}
+  BFS(Digraph<T> G, T root) : G(G), root(root) {}
 
   //
   std::map<T, std::set<T>> run();
@@ -20,7 +20,7 @@ public:
   //
   std::map<T, bool> initExplore();
 private:
-  Graph<T> G;
+  Digraph<T> G;
   T root;
 };