diff --git a/TinySTL/BinarySearchTree.h b/TinySTL/BinarySearchTree.h
index e32d7a1..14e212a 100644
--- a/TinySTL/BinarySearchTree.h
+++ b/TinySTL/BinarySearchTree.h
@@ -17,6 +17,7 @@ namespace TinySTL{
 		friend class bst_iter;
 	private:
 		struct node{
+			typedef T value_type;
 			T data_;
 			node *left_;
 			node *right_;
@@ -37,6 +38,14 @@ namespace TinySTL{
 		}
 
 		void insert(const T& val);
+		template<class Iterator>
+		void insert(Iterator first, Iterator last);
+
+		bool empty()const{ return root_ == 0; }
+
+		iterator find_min();
+		iterator find_max();
+		iterator find(const T& val);
 
 		void print_preorder(const string& delim = " ", std::ostream& os = std::cout)const;
 		void print_inorder(const string& delim = " ", std::ostream& os = std::cout)const;
@@ -50,12 +59,15 @@ namespace TinySTL{
 			}
 		}
 		void insert_elem(const T& val, node *&ptr);
+		iterator find_min_aux(node *ptr);
+		iterator find_max_aux(node *ptr);
+		iterator find_aux(const T& val, node *ptr);
 		void print_preorder_aux(const string& delim, std::ostream& os, const node *ptr)const;
 		void print_inorder_aux(const string& delim, std::ostream& os, const node *ptr)const;
 		void print_postorder_aux(const string& delim, std::ostream& os, const node *ptr)const;
 	};//end of bst class
 	template<class T>
-	void binary_search_tree<T>::insert_elem(const T& val, node *&ptr){
+	void binary_search_tree<T>::insert_elem(const T& val, node *&ptr){//重复的元素不插入
 		if (ptr == 0){
 			ptr = nodeAllocator::allocate();
 			ptr->data_ = val;
@@ -75,6 +87,12 @@ namespace TinySTL{
 		insert_elem(val, root_);
 	}
 	template<class T>
+	template<class Iterator>
+	void binary_search_tree<T>::insert(Iterator first, Iterator last){
+		for (; first != last; ++first)
+			insert(*first);
+	}
+	template<class T>
 	void binary_search_tree<T>::print_preorder_aux(const string& delim, std::ostream& os, const node *ptr)const{
 		if (ptr){
 			os << ptr->data_ << delim;
@@ -110,11 +128,62 @@ namespace TinySTL{
 	void binary_search_tree<T>::print_postorder(const string& delim, std::ostream& os)const{
 		print_postorder_aux(delim, os, root_);
 	}
+	template<class T>
+	typename binary_search_tree<T>::iterator binary_search_tree<T>::find_min_aux(node *ptr){
+		while (ptr && ptr->left_ != 0){
+			ptr = ptr->left_;
+		}
+		return iterator(ptr);
+	}
+	template<class T>
+	typename binary_search_tree<T>::iterator binary_search_tree<T>::find_min(){
+		return find_min_aux(root_);
+	}
+	template<class T>
+	typename binary_search_tree<T>::iterator binary_search_tree<T>::find_max_aux(node *ptr){
+		while (ptr && ptr->right_ != 0){
+			ptr = ptr->right_;
+		}
+		return iterator(ptr);
+	}
+	template<class T>
+	typename binary_search_tree<T>::iterator binary_search_tree<T>::find_max(){
+		return find_max_aux(root_);
+	}
+	template<class T>
+	typename binary_search_tree<T>::iterator binary_search_tree<T>::find_aux(const T& val, node *ptr){
+		while (ptr){
+			if (val == ptr->data_)
+				break;
+			else if (val < ptr->data_)
+				ptr = ptr->left_;
+			else
+				ptr = ptr->right_;
+		}
+		return iterator(ptr);
+	}
+	template<class T>
+	typename binary_search_tree<T>::iterator binary_search_tree<T>::find(const T& val){
+		return find_aux(val, root_);
+	}
 
 	namespace{
 		//class of bst iterator
-		template<class T>
-		class bst_iter{};
+		template<class T>//T = node
+		class bst_iter{
+		private:
+			typedef typename binary_search_tree<typename T::value_type>::vaule_type value_type;
+			typedef typename binary_search_tree<typename T::value_type>::reference reference;
+			typedef typename T::value_type *pointer;
+		private:
+			T *ptr_;
+		public:
+			bst_iter(T *ptr) :ptr_(ptr){}
+
+			operator T*(){ return ptr_; }
+			reference operator*(){ return ptr_->data_; }
+			pointer operator ->(){ return &(operator*()); }
+		};
 	}
 }