diff --git a/TinySTL/Detail/Graph.impl.h b/TinySTL/Detail/Graph.impl.h
index 146015a3501f8fd9f281a11942b0fefc8823cf4f..a3118d92da83610dedc4eaa281ffef5fce109378 100644
--- a/TinySTL/Detail/Graph.impl.h
+++ b/TinySTL/Detail/Graph.impl.h
@@ -42,12 +42,27 @@ namespace TinySTL{
 				if (equal_func(pair.first.first, index))
 					return bucket_iterator(this, (pair.second).end());
 			}
-			throw std::exception("return end error");
+			//throw std::exception("return end error");
+			return bucket_iterator();
 		}
 		template<class Index, class Value, class EqualFunc>
 		size_t graph<Index, Value, EqualFunc>::size()const{
 			return size_;
 		}
+		template<class Index, class Value, class EqualFunc>
+		typename graph<Index, Value, EqualFunc>::node_sets 
+			graph<Index, Value, EqualFunc>::adjacent_nodes(const Index& index){
+			node_sets s;
+			for (auto it = begin(index); it != end(index); ++it){
+				s.push_back(*it);
+			}
+			return s;
+		}
+		template<class Index, class Value, class EqualFunc>
+		typename graph<Index, Value, EqualFunc>::node_sets
+			graph<Index, Value, EqualFunc>::adjacent_nodes(const node& n){
+			return adjacent_nodes(n.first);
+		}
 		//********************************************************************************
 		template<class Index, class Value, class EqualFunc>
 		graph_iterator<Index, Value, EqualFunc>& graph_iterator<Index, Value, EqualFunc>::operator ++(){
diff --git a/TinySTL/Graph.h b/TinySTL/Graph.h
index 84bdb3a1aa28160d2ff424dd13f14fcd784328df..460aad2302c4108a1fe196a1b14cc0219c4ef689 100644
--- a/TinySTL/Graph.h
+++ b/TinySTL/Graph.h
@@ -30,14 +30,15 @@ namespace TinySTL{
 			virtual ~graph(){};
 			virtual void add_node(const node& item, const node_sets& nodes) = 0;
 			//virtual void delte_node(const node& item) = 0;
-			//virtual node_sets adjacent_nodes(const node& n) = 0;
-			//virtual node_sets adjacent_nodes(const Index& index) = 0;
 			//virtual void DFS(visiter_func_type func) = 0;
 			//virtual void BFS(visiter_func_type func) = 0;
 
 			static node& new_node(const Index& index, const Value& val);
 			bool is_contained(const Index& index);
 			inline static node_sets empty_node_set();
+			node_sets adjacent_nodes(const Index& index);
+			node_sets adjacent_nodes(const node& n);
+
 			inline bool empty()const;
 			inline size_t size()const;
 			inline bucket_iterator begin(const Index& index);
@@ -56,7 +57,7 @@ namespace TinySTL{
 			typedef graph<Index, Value, EqualFunc> graph_type;
 			typedef typename list<typename graph_type::node>::iterator inner_it_type;
 		public:
-			graph_iterator(cntrPtr c, inner_it_type iit)
+			explicit graph_iterator(cntrPtr c = nullptr, inner_it_type iit = inner_it_type())
 				:container_(c), inner_it_(iit){}
 			graph_iterator& operator ++();
 			const graph_iterator operator ++(int);