Refactor: Replace std::map and std::set with unordered versions

graph/digraph.h

@@ -11,7 +11,7 @@ class Digraph : public Graph<T> {
 public:
   Digraph() = default;
 
-  Digraph(std::map<T, std::set<T>> G);
+  Digraph(std::unordered_map<T, std::unordered_set<T>> G);
 
   // Return true if there is a path from u to v
   bool contains(const T& u, const T& v);
@@ -27,7 +27,7 @@ public:
 };
 
 template<typename T>
-Digraph<T>::Digraph(std::map<T, std::set<T>> G) {
+Digraph<T>::Digraph(std::unordered_map<T, std::unordered_set<T>> G) {
   this->adjList = G;
 }
 
@@ -49,7 +49,7 @@ void Digraph<T>::remove(const T& u, const T& v) {
 
 template<typename T>
 auto Digraph<T>::reverse() {
-  std::map<T, std::set<T>> revMatrix;
+  std::unordered_map<T, std::unordered_set<T>> revMatrix;
   
   for (const auto& u : this->vertices()) {
     for (const auto& v : this->adjList[u]) {