BinarySearchTree

#pragma once// Binary Search Tree Nodetemplate<class K, class V>struct BSTNode{K _key;// 节点关键值V _value;// 节点数据BSTNode* _left;// 左孩子BSTNode* _right;// 右孩子BSTNode(const K& key, const V& data):_key(key),_value(data),_left(NULL),_right(NULL){}};template<class K, class V>class BSTree{typedef BSTNode<K, V> Node;public:BSTree():_root(NULL){}~BSTree(){}BSTree(const BSTree& t);BSTree&operator=(const BSTree& t);public:BSTNode<K,V>* Find_R(const K& key){return _Find(_root, key);}bool Insert_R(const K& key, const V& data){return _Insert(_root, key, data);}bool Remove_R(const K& key){return _Remove(_root, key);}void PrevOrder(){_PrevOrder(_root);cout<<endl;}Node* Find(const K& key){Node* cur = _root;while(cur){if (cur->_key > key){cur = cur->_left;}else if (cur->_key < key){cur = cur->_right;}else{return cur;}}return NULL;}bool Remove(const K& key){if (_root == NULL){return false;}else if (_root->_left == NULL && _root->_right == NULL){delete _root;_root = NULL;return true;}Node* parent = NULL;Node* del = _root;while (del){if (del->_key > key){parent = del;del = del->_left;}else if (del->_key < key){parent = del;del = del->_right;}else{break;}}if (del){// 左树为空，则用右树调补if (del->_left == NULL){// 注意删除节点为根节点的情况if (_root != del){if(del == parent->_left)parent->_left = del->_right;elseparent->_right = del->_right;}else{_root = del->_right;}}else if (del->_right == NULL){// 注意删除节点为根节点的情况if (_root != del){if(del == parent->_left)parent->_left = del->_left;elseparent->_right = del->_left;}else{_root = del->_right;}}else{// 查找右子树的中序遍历的第一个节点Node* subRight = del->_right; Node* firstInOrder = del->_right;Node* parent = del;while(firstInOrder->_left){parent = firstInOrder;firstInOrder = firstInOrder->_left;}swap(del->_key, firstInOrder->_key);swap(del->_value, firstInOrder->_value);if (firstInOrder == parent->_left){parent->_left = firstInOrder->_right;}else{parent->_right = firstInOrder->_right;}del = firstInOrder;}delete del;}else{return false;}return true;}bool Insert(const K& key, const V& value){if (_root == NULL){_root = new Node(key, value);return true;}Node* parent = NULL;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{return false;}}if (parent->_key < key)parent->_right = new Node(key, value);elseparent->_left = new Node(key, value);return true;}protected:void _PrevOrder(BSTNode<K,V>* root){if (root){_PrevOrder(root->_left);//cout<<"[key:"<<root->_key<<","<<root->_value<<"]"<<"->";cout<<root->_key<<", ";_PrevOrder(root->_right);}}BSTNode<K,V>* _Find(BSTNode<K,V>* root, const K& key){if (root){if (root->_key > key){return _Find(root->_left, key);}else if (root->_key < key){return _Find(root->_right, key);}else{return root;}}return NULL;}bool _Insert(BSTNode<K,V>*& root, const K& key, const V& data){if (root == NULL){root = new BSTNode<K,V>(key, data);return true;}else{if (root->_key > key){return _Insert(root->_left, key, data);}else if (root->_key < key){return _Insert(root->_right, key, data);}else{return false;}}}bool _Remove(BSTNode<K,V>*& root, const K& key){if (root){if(root->_key > key){return _Remove(root->_left, key);}else if(root->_key < key){return _Remove(root->_right, key);}else{// 1.如果左or右子树为空，则用一个子树进行填补。// 2.如果左右均不为空，则使用右子树中序的第一个节点填补if (root->_left == NULL){BSTNode<K,V>* del = root;root = root->_right;delete del;}else if(root->_right == NULL){BSTNode<K,V>* del = root;root = root->_left;delete del;}else{// 查找右子树的中序遍历的第一个节点BSTNode<K,V>* right = root->_right;while (right->_left){right = right->_left;}swap(root->_value, right->_value);swap(root->_key, right->_key);_Remove(root->_right, right->_key);}return true;}}return false;}private:BSTNode<K,V>* _root;};void TestBSTree(){// 5 3 4 1 7 8 2 6 0 9BSTree<int, double> t;t.Insert(5,5);t.Insert(3,3);t.Insert(4,4);t.Insert(1,1);t.Insert(7,7);t.Insert(8,8);t.Insert(2,2);t.Insert(6,6);t.Insert(0,0);t.Insert(9,9);t.PrevOrder();BSTNode<int,double>* ret = t.Find(9);cout<<"Find 9 ?: "<<ret->_key<<endl;ret = t.Find(10);cout<<"Find 10 ?: "<<ret<<endl;t.Remove(8);t.Remove(1);t.Remove(5);t.PrevOrder();}