1、二叉搜索树的实现

        二叉搜索树的拥有很快的查找速度，查找的效率为O（logN)，也就是说如果把全国的人放到二叉搜索树中，最多只需要31次就可以 找到你，这是一种很快的搜索方式，他还有两种模型一种是key模型，还有是key/value模型接下来我将一步一步的带你实现二叉搜索树，以key/value为例，首先是他的结点

	template<class K, class V>struct BSTreeNode{BSTreeNode<K, V>* _left;BSTreeNode<K, V>* _right;K _key;V _value;BSTreeNode(const K& n, const V& v):_key(n), _left(nullptr), _right(nullptr), _value(v){}};

先把结点定义好，在写插入函数 （注意事项已经写进代码了）

	template<class K, class V>class BSTree//Binary Search Tree{typedef BSTreeNode<K, V> Node;//这里只在内部typedef是怕与外面混淆public:bool Insert(const K& key, const V& value){if (_root == nullptr)//如果二叉树没有创建根节点就创建{_root = new Node(key, value);return true;}Node* cur = _root;Node* parent = nullptr;int flag = 0;//去找空结点找到就插入，找到相同的就返回while (cur){if (cur->_key < key){parent = cur;cur = cur->_right;flag = 1;}else if (cur->_key > key){parent = cur;cur = cur->_left;flag = 0;}else{return false;}}cur = new Node(key, value);if (flag == 1)//这里是确定标志位，看看要插入的是左节点还是右节点{parent->_right = cur;}else{parent->_left = cur;}return true;}

实现了插入函数以后就是查找函数， 查找函数就是通过key值来查找value

		Node* Find(const K& key){Node* cur = _root;while (cur){if (cur->_key < key)cur = cur->_right;else if (cur->_key > key)cur = cur->_left;elsereturn cur;}return nullptr;}

 最难的就是删除了，删除需要注意三个地方，如果左子树为空、如果右子树为空和如果左右子树都不为空。（很抽象，一定要画图！！！）

		bool Erase(const K& key){Node* parent = nullptr;Node* cur = _root;while (cur){if (cur->_key < key){parent = cur;cur = cur->_right;}else if (cur->_key > key){parent = cur;cur = cur->_left;}else{//左边是空结点if (cur->_left == nullptr){if (cur == _root)//避免parent为nullptr{_root = cur->_right;}else{if (parent->_right == cur)parent->_right = cur->_right;elseparent->_left = cur->_right;}delete cur;return true;}else if (cur->_right == nullptr){if (cur == _root)//避免parent为nullptr{_root = cur->_left;}else{if (parent->_right == cur)parent->_right = cur->_left;elseparent->_left = cur->_left;}delete cur;return true;}else//两边都不为空结点{Node* rightmin = cur->_right;Node* rightminparent = cur;while (rightmin->_left){rightminparent = rightmin;rightmin = rightmin->_left;}cur->_key = rightmin->_key;if (rightminparent->_right == rightmin)rightminparent->_right = rightmin->_right;elserightminparent->_left = rightmin->_right;delete rightmin;return true;}}}return false;}

2、二叉搜索树的使用

这里贴一个示例代码

	void test(){BSTree<string, string> b;b.Insert("string", "字符串");b.Insert("sort", "排序");b.Insert("insert", "插入");b.Insert("tree", "树");//string str;//while (cin >> str)//{//	BSTreeNode<string, string>*ret = b.Find(str);//	if (ret)//	{//		cout << ret->_value << endl;//	}//	else//	{//		cout << "无此单词"<<endl;//	}//}string strArr[] = { "西瓜","西瓜" ,"香蕉","西瓜" ,"西瓜" ,"香蕉","西瓜" ,"西瓜" ,"蜜瓜" ,"西瓜" ,"西瓜","西瓜","西瓜","西瓜","香蕉","香蕉" ,"香蕉" ,"香蕉" };BSTree<string,int> countTree;for (auto str : strArr){BSTreeNode<string, int>* ret = countTree.Find(str);if (ret == nullptr){countTree.Insert(str, 1);}else{ret->_value++;}}countTree.InOrder();}

去试试吧