diff --git a/thu_dsa/chp6/Graph.h b/thu_dsa/chp6/Graph.h
index 83a904f..81119ea 100644
--- a/thu_dsa/chp6/Graph.h
+++ b/thu_dsa/chp6/Graph.h
@@ -13,11 +13,11 @@ template <typename Tv, typename Te>
 class Graph{
 private:
 	void reset();										//reset all information of all vertices and edges
-	void BFS(int, int&);
-	void DFS(int, int&);
-	void BCC(int, int&, Stack<int>&);
-	bool TSort(int, int&, Stack<Tv>*);
-	template <typename PU> void PFS(int, PU);
+	void BFS(int, int&);								//Breadth First Search
+	void DFS(int, int&);								//Depth First Search
+	void BCC(int, int&, Stack<int>&);					//Biconnected Component
+	bool TSort(int, int&, Stack<Tv>*);					//Topological Sort
+	template <typename PU> void PFS(int, PU);			//Priority First Search
 
 public:
 	int num_of_vertices;
@@ -52,7 +52,7 @@ public:
 	void prim(int);
 	void dijkstra(int);
 	Stack<Tv>* tSort(int);
-	template <typename PU> void pfd(int, PU);
+	template <typename PU> void pfs(int, PU);
 };
 
 //private methods
@@ -60,7 +60,7 @@ template <typename Tv, typename Te>
 void Graph<Tv, Te>::reset(){//reset all information of all vertices and edges
 	for(int ix = 0; ix != num_of_vertices; ++ix){
 		status(ix)   = UNDISCOVERED;
-		priority(ix) = 0;
+		priority(ix) = INT_MAX;
 		dtime(ix)    = -1;
 		ftime(ix)    = -1;
 		parent(ix)   = -1;
@@ -118,6 +118,85 @@ void Graph<Tv, Te>::DFS(int x, int& clock){
 	status(x) = VISITED;
 }
 
+#define hca(x) ftime(x)
+template <typename Tv, typename Te>
+void Graph<Tv, Te>::BCC(int x, int &clock, Stack<int> &S) {
+	status(x) = DISCOVERED;
+	S.push(x);
+	hca(x) = dtime(x) = ++clock;
+	for (int v = firstNeighbor(x); v != -1; v = nextNeighbor(x, v)) {
+		switch (status(v)) {
+		case UNDISCOVERED:
+			type(x, v) = TREE;
+			BCC(v, clock, S);
+			if (hca(v) < dtime(x)) hca(x) = MIN(hca(v), hca(x));
+			else {//a biconnected component found
+				while (S.pop() != x);
+				S.push(x);
+			}
+			break;
+
+		case DISCOVERED:
+			type(x, v) = BACKWARD;
+			if (parent(x) != v) hca(x) = MIN(hca(x), dtime(v));
+			break;
+
+		case VISITED:
+		default:
+			type(x, v) = dtime(x) < dtime(v) ? FORWARD : CROSS;
+			break;
+		}
+	}
+}
+#undef hca
+
+template <typename Tv, typename Te>
+bool Graph<Tv, Te>::TSort(int x, int &clock, Stack<Tv> *S){
+	status(x) = DISCOVERED;
+	dtime(x)  = ++clock;
+	for(int v = firstNeighbor(x); v != -1; v = nextNeighbor(x, v)){
+		switch(status(v)){
+		case UNDISCOVERED:
+			status(v) = DISCOVERED;
+			type(x, v) = TREE;
+			if (!TSort(v, clock, S)) return false;
+			break;
+
+		case DISCOVERED:
+			type(x, v) = BACKWARD;
+			return false;
+
+		case VISITED:
+		default:
+			type(x, v) = dtime(x) > dtime(v)? FORWARD: CROSS;
+			break;
+		}
+	}
+	S->push(x);
+	return true;
+}
+
+template <typename Tv, typename Te>
+template <typename PU>
+void Graph<Tv, Te>::PFS(int x, PU PrioUpdater){
+	priority(x) = 0;
+	status(x)   = VISITED;
+	parent(x)   = -1;
+	while(1){
+		for (int v = firstNeighbor(x); v != -1; v = nextNeighbor(x, v))
+			PrioUpdater(this, x, v);
+		//find current highest priority
+		for (int shortest = INT_MAX, v = 0; v != num_of_vertices; ++v)
+			if (status(v) == UNDISCOVERED && priority(v) < shortest) {
+				shortest = priority(v);
+				x        = v;
+			}
+		if (status(x) == VISITED) break;
+		status(x) == VISITED;
+		type(parent(x), x) = TREE;
+	}
+}
+
 //Graph related algorithms
 
 template <typename Tv, typename Te>
@@ -142,4 +221,83 @@ void Graph<Tv, Te>::dfs(int start){
 	} while ((x = ++x % num_of_vertices) != start);
 }
 
-#endif
\ No newline at end of file
+template <typename Tv, typename Te>
+void Graph<Tv, Te>::bcc(int start){
+	reset();
+	int clock = 0;
+	int curr  = start;
+	Stack<int> S;
+	do{
+		if (status(curr) == UNDISCOVERED) {
+			BCC(curr, clock, S);
+			S.pop();	//remove the last element in the Stack, which is the start point of current connected components
+		}
+	} while ((curr = ++curr % num_of_vertices) ŁĄ = start);
+}
+
+//Prim Algorithm
+template <typename Tv, typename Te>
+class PrimPU{
+public:
+	void operator()(Graph<Tv, Te> *G, int parent, int v){
+		if(G->status(v) == UNDISCOVERED){
+			if (G->weight(parent, v) < G->priority(v)) {
+				G->priority = G->weight(parent, v);
+				G->parent(v) = parent;
+			}
+		}
+	}
+};
+
+template <typename Tv, typename Te>
+void Graph<Tv, Te>::prim(int x){
+	pfs(x, PrimPU<Tv, Te>());
+}
+
+//Dijkstra Algorithm
+
+template <typename Tv, typename Te>
+class DijkstraPU{
+public:
+	void operator()(Graph<Tv, Te> *G, int parent, int v){
+		if(G->status(v) == UNDISCOVERED){
+			if(G->priority(parent) + G->weight(parent, v) < G->priority(v)){
+				G->priority(v) = G->priority(parent) + G->weight(parent, v);
+				G->parent(v) = parent;
+			}
+		}
+	}
+};
+
+template <typename Tv, typename Te>
+void Graph<Tv, Te>::dijkstra(int x){
+	pfs(x, DijkstraPU<Tv, Te>());
+}
+
+template <typename Tv, typename Te>
+Stack<Tv>* Graph<Tv, Te>::tSort(int start){
+	reset();
+	Stack<Tv> *S;
+	int clock = 0;
+	int curr  = start;
+	do{
+		if(status(curr) == UNDISCOVERED && !TSort(curr, clock, S)){
+			while (!S->empty()) S->pop();
+			break;
+		}
+	} while ((curr = ++curr % num_of_vertices) != start);
+	return S;
+}
+
+template <typename Tv, typename Te>
+template <typename PU> 
+void Graph<Tv, Te>::pfs(int start, PU PrioUpdater){
+	reset();
+	int curr = start;
+	do{
+		if (status(curr) == UNDISCOVERED)
+			PFS(curr, PrioUpdater);
+	} while ((curr = ++curr % num_of_vertices) != start);
+}
+
+#endif
diff --git a/thu_dsa/chp6/Graph.md b/thu_dsa/chp6/Graph.md
new file mode 100644
index 0000000..4863354
--- /dev/null
+++ b/thu_dsa/chp6/Graph.md
@@ -0,0 +1,2 @@
+Conclusion on Chapter Six: Graph
+================================
\ No newline at end of file
diff --git a/thu_dsa/chp6/Vertex.h b/thu_dsa/chp6/Vertex.h
index dce10ff..55a3de0 100644
--- a/thu_dsa/chp6/Vertex.h
+++ b/thu_dsa/chp6/Vertex.h
@@ -11,7 +11,7 @@ public:
 	int parent     = -1;
 	int dTime      = -1;
 	int fTime      = -1;
-	int priority   = 0;
+	int priority   = INT_MAX;
 	int inDegree   = 0;
 	int outDegree  = 0;