Move Graph::vertices to Digraph

graph/graph.h

@@ -4,6 +4,7 @@
 #include <map>
 #include <set>
 #include <ostream>
+#include <ranges>
 
 namespace graph {
 
@@ -17,13 +18,16 @@ public:
   ~Graph();
   
   // Return true if there is a path from u to v
-  virtual bool contains(const T& u, const T& v) = 0;
+  virtual bool contains(const T& u, const T& v) =0;
 
   // Add edge e(u,v)
-  virtual void insert(const T& u, const T& v) = 0;
+  virtual void insert(const T& u, const T& v) =0;
 
   // Remove edge e(u,v)
-  virtual void remove(const T& u, const T& v) = 0;
+  virtual void remove(const T& u, const T& v) =0;
+
+  // Return graph vertices
+  auto vertices();
 
   // Return num. of vertices
   std::uint16_t V();
@@ -42,6 +46,11 @@ Graph<T>::~Graph() {
   adjMatrix.clear();
 }
 
+template<typename T>
+auto Graph<T>::vertices() {
+  return std::views::keys(adjMatrix);
+}
+
 template<typename T>
 std::uint16_t Graph<T>::V() {
   return static_cast<std::uint16_t>(adjMatrix.size());
@@ -50,8 +59,8 @@ std::uint16_t Graph<T>::V() {
 template<typename T>
 std::uint16_t Graph<T>::E() {
   std::uint16_t edges = 0;
-  for (const auto& v : adjMatrix) {
-    edges += static_cast<std::uint16_t>(v.second.size());
+  for (const auto& u : vertices()) {
+    edges += static_cast<std::uint16_t>(adjMatrix[u].size());
   }
   return static_cast<std::uint16_t>(edges);
 }
@@ -59,10 +68,10 @@ std::uint16_t Graph<T>::E() {
 template<typename T>
 std::ostream& operator<<(std::ostream& os, Graph<T>& G) {
   os << "V: " << G.V() << " E: " << G.E() << '\n';
-  for (const auto& u : G.adjMatrix) {
-    if (!u.second.empty()) {
-      for (const auto& v : u.second) {
-        os << u.first << "->" << v << ' ';
+  for (const auto& u : this->vertices()) {
+    if (!this->adjMatrix[u].empty()) {
+      for (const auto& v : this->adjMatrix[u]) {
+        os << u << "->" << v << ' ';
       }
       os << '\n';
     }