C++实现搜索二叉树

#pragma once
using namespace std;
template
struct BSTreeNode
{
	BSTreeNode* _left;
	BSTreeNode* _right;
	K _key;
	BSTreeNode(const K& key)
		:_left(nullptr)
		, _right(nullptr)
		, _key(key)
	{}
};

template
struct BSTree
{
	typedef BSTreeNode Node;
public:
	BSTree()
		:_root(nullptr)
	{}

	bool Insert(const K& key)
	{
		if (_root == nullptr)
		{
			_root = new Node(key);
			return true;
		}
		Node* parent = nullptr;
		Node* cur = _root;
		while (cur)
		{
			if (cur->_key > key)
			{
				parent = cur;
				cur = cur->_left;
			}
			else if (cur->_key < key)
			{
				parent = cur;
				cur = cur->_right;
			}
			else
				return false;
		}
		cur = new Node(key);
		if (parent->_key > key)
		{
			parent->_left = cur;
		}
		else if (parent->_key < key)
		{
			parent->_right = cur;
		}
		return true;
	}
	bool 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 true;
		}
		return false;
	}

	void InOrder()
	{
		_InOrder(_root);
		cout << endl;

	}

	void _InOrder(Node* root)
	{
		if (root == nullptr)
		{
			return;
		}
		_InOrder(root->_left);
		cout << root->_key << " ";
		_InOrder(root->_right);
	}
	bool Erase(const K& key)
	{
		Node* parent = nullptr;
		Node* cur = _root;
		while (cur)
		{
			if (cur->_key > key)
			{
				parent = cur;
				cur = cur->_left;
			}
			else if (cur->_key < key)
			{
				parent = cur;
				cur = cur->_right;
			}
			else
			{
				//找到，开始删除
				if (cur->_left == nullptr)
				{
					if (parent == nullptr)
					{
						_root = cur->_right;
					}
					else
					{
						if (parent->_left == cur)
							parent->_left = cur->_right;
						else
							parent->_right = cur->_right;
					}
					delete cur;
				}
				else if (cur->_right == nullptr)
				{
					if (parent == nullptr)
					{
						_root = cur->_left;
					}
					else
					{
						if (parent->_left == cur)
							parent->_left = cur->_left;
						else
							parent->_right = cur->_left;
					}
					delete cur;
				}
				else
				{
					Node* minparent = cur;
					Node* min = cur->_right;
					while (min->_left)
					{
						minparent = min;
						min = min->_left;
					}
					cur->_key = min->_key;
					if (minparent->_left == min)
						minparent->_left = min->_right;
					else
						minparent->_right = min->_right;
					delete min;
				}
				return true;
			}
		}
		return false;
	}

	bool _InsertR(Node*& root, const K& key)
	{
		if (root == nullptr)
		{
			root = new Node(key);
			return true;
		}
		if (root->_key > key)
		{
			return _InsertR(root->_left, key);
		}
		else if (root->_key < key)
		{
			return _InsertR(root->_right, key);
		}
		else
			return false;
	}

	bool InsertR(const K& key)
	{
		return _InsertR(_root, key);
	}

	bool _EraseR(Node*& root, const K& key)
	{
		if (root == nullptr)
		{
			return false;
		}
		if (root->_key > key)
		{
			return _EraseR(root->_left, key);
		}
		else if (root->_key < key)
		{
			return _EraseR(root->_right, key);
		}
		else
		{
			Node* del = root;
			if (root->_left == nullptr)
				root = root->_right;
			else if (root->_right == nullptr)
				root = root->left;
			else
				delete del;
		}
			
	}

	Node* EraseR(const K& key)
	{
		return _EraseR(_root, key);
	}

private:
	Node* _root;
};