Add operator<< for graph types, add contains query for digraph types and normalize scc

graph/graph.h

@@ -3,38 +3,38 @@
 
 #include <map>
 #include <set>
-#include <iostream>
+#include <ostream>
 
 namespace graph {
 
+// Forward declerations
+template<typename T> class Graph;
+template<typename T> std::ostream& operator<<(std::ostream& os, Graph<T>& G);
+
 template<typename T>
 class Graph {
 public:
   ~Graph();
+  
+  // Return true if there is a path from u to v
+  virtual bool contains(const T& u, const T& v) = 0;
 
   // Add edge e(u,v)
-  virtual void insert(const T& u, const T& v);
-
-  // Return true if e(u,v) exists
-  virtual bool contains(const T& u, const T& v);
-
-  // Return true if vertex u exists
-  virtual bool contains(const T& u);
+  virtual void insert(const T& u, const T& v) = 0;
 
   // Remove edge e(u,v)
-  virtual void remove(const T& u, const T& v);
+  virtual void remove(const T& u, const T& v) = 0;
 
   // Return num. of vertices
-  virtual std::uint16_t V();
+  std::uint16_t V();
 
   // Return num. of edges
-  virtual std::uint16_t E();
-
-  // Output graph
-  virtual void output();
+  std::uint16_t E();
 
   // Adjacency matrix representation
   std::map<T, std::set<T>> adjMatrix;
+
+  friend std::ostream& operator<<<>(std::ostream& os, Graph<T>& G);
 };
 
 template<typename T>
@@ -42,27 +42,6 @@ Graph<T>::~Graph() {
   adjMatrix.clear();
 }
 
-template<typename T>
-inline void Graph<T>::insert(const T& u, const T& v) {
-  Graph<T>::adjMatrix[u].insert(v);
-  Graph<T>::adjMatrix[v];
-}
-
-template<typename T>
-bool Graph<T>::contains(const T& u, const T& v) {
-  return adjMatrix[u].contains(v);
-}
-
-template<typename T>
-bool Graph<T>::contains(const T& u) {
-  return adjMatrix.contains(u);
-}
-
-template<typename T>
-void Graph<T>::remove(const T& u, const T& v) {
-  adjMatrix[u].erase(v);
-}
-
 template<typename T>
 std::uint16_t Graph<T>::V() {
   return static_cast<std::uint16_t>(adjMatrix.size());
@@ -78,14 +57,18 @@ std::uint16_t Graph<T>::E() {
 }
 
 template<typename T>
-void Graph<T>::output() {
-  for (const auto& v : adjMatrix) {
-    for (const auto& u : v.second) {
-      std::cout << v.first << "->" << u << '|';
+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 << ' ';
+      }
+      os << '\n';
     }
-    std::cout << '\n';
   }
-  std::cout << '\n';
+  os << '\n';
+  return os;
 }
 
 } // namespace graph