Add custom equality comparison for SCCs

graph/scc.h

@@ -17,12 +17,19 @@ public:
 
   //
   T representative() { return proxy; };
+
+  bool operator==(const SCC& o) const;
 private:
   // Each SCC has a representative vertex that helps
   // answer strong connectivity queries in O(1) time
   T proxy;
 };
 
+template<typename T>
+bool SCC<T>::operator==(const SCC& o) const{
+  return proxy == o.proxy;
+}
+
 }; // namespace graph
 
 #endif