Switched from the bulky style of header safety to the 'pragma once' style

graph.h

@@ -1,5 +1,4 @@
-#ifndef GRAPH_H
+#pragma once
-#define GRAPH_H
 #include <new>
 #include <utility>
 
@@ -37,5 +36,3 @@ public:
     Graph(const Graph&) = delete;
     Graph& operator=(const Graph&) = delete;
 };
-
-#endif