#pragma once

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

template<class K>
class BSTree
{
	typedef BSTreeNode<K> Node;
public:
	Node* Find(const K& key)
	{
		if (_root == nullptr)
		{
			return nullptr;
		}
		Node* cur = _root;
		while (cur != nullptr)
		{
			if (key > cur->_key)
			{
				cur = cur->_right;
			}
			else if (key < cur->_key)
			{
				cur = cur->_left;
			}
			else
			{
				return cur;
			}
		}
		return nullptr;
	}
	bool Insert(const K& key)
	{
		if (_root == nullptr)
		{
			_root = new Node(key);
			return true;
		}
		Node* cur = _root;
		Node* parent = nullptr;
		while (cur != nullptr)
		{
			if (key> cur->_key)
			{
				parent = cur;
				cur = cur->_right;
			}
			else if (key < cur->_key)
			{
				parent = cur;
				cur = cur->_left;
			}
			else
			{
				return false;
			}
		}
		cur = new Node(key);
		if (key > parent->_key)
		{
			parent->_right = cur;
		}
		else
		{
			parent->_left = cur;
		}
		return true;
	}
	bool Erase(const K& key)
	{
		if (_root == nullptr)
		{
			return false;
		}
		Node* cur = _root;
		Node* parent = nullptr;
		while (cur != nullptr)
		{
			if (key > cur->_key)
			{
				parent = cur;
				cur = cur->_right;
			}
			else if (key < cur->_key)
			{
				parent = cur;
				cur = cur->_left;
			}
			else
			{
				// ҵ
				if (cur->_left == nullptr)
				{
					if (parent == nullptr)
					{
						_root = cur->_right;
					}
					else
					{
						if (cur == parent->_left)
						{
							parent->_left = cur->_right;
						}
						else
						{
							parent->_right = cur->_right;
						}
					}
					delete cur;
					return true;
				}
				else if (cur->_right == nullptr)
				{
					if (parent == nullptr)
					{
						_root = cur->_left;
					}
					else
					{
						if (cur == parent->_left)
						{
							parent->_left = cur->_left;
						}
						else
						{
							parent->_right = cur->_left;
						}
					}
					delete cur;
					return true;
				}
				else
				{
					// 滻ɾ
					Node* rightMin = cur->_right;
					Node* rightMinParent = cur;
					while (rightMin->_left != nullptr)
					{
						rightMinParent = rightMin;
						rightMin = rightMin->_left;
					}
					cur->_key = rightMin->_key;
					// rightMin
					if (rightMin == rightMinParent->_left)
					{
						rightMinParent->_left = rightMin->_right;
					}
					else
					{
						rightMinParent->_right = rightMin->_right;
					}
					delete rightMin;
					return true;
				}
			}
		}
		return false;
	}

	void InOrder()
	{
		_InOrder(_root);
		cout << endl;
	}
private:
	void _InOrder(Node* root)
	{
		if (root == nullptr)
			return;
		_InOrder(root->_left);
		//cout << root->_kv.first << ":" << root->_kv.second << endl;
		cout << root->_key << " ";
		_InOrder(root->_right);
	}
	Node* _root = nullptr;
};