BinaryTreecpp

#include
#include
using namespace std;
template
struct BSTNode
{
T _val;
BSTNode* _left;
BSTNode* _right;

BSTNode(const T& val = T())
	: _val(val)
	, _left(nullptr)
	, _right(nullptr)
{

}

};

template
class BSTree
{
public:
typedef BSTNode Node;

Node* find(const T& val)
{
	Node* cur = _root;
	while (cur)
	{
		if (cur->_val == val)
			return cur;
		else if (cur->_val < val)
			cur = cur->_right;
		else
			cur = cur->_left;
	}
	return nullptr;
}
bool insert(const T& val)
{
	if (_root == nullptr)
	{
		_root = new Node(val);
		return true;

	}
	Node* cur = _root;
	Node* parent = nullptr;
	//查找插入的位置
	while (cur)
	{
		parent = cur;
		if (cur->_val == val)
			return false;
		else if (cur->_val < val)
			cur = cur->_right;
		else
			cur = cur->_left;
	}

	cur = new Node(val);
	//判断放在哪边
	if (parent->_val < val)
		parent->_right = cur;
	else
		parent->_left = cur;
	return true;
}
bool erase(const T& val)
{
	Node* cur = _root;
	Node* parent = nullptr;
	while (cur)
	{
		if (cur->_val == val)
			break;
		else if (cur->_val < val)
		{
			parent = cur;
			cur = cur->_right;
		}
		else
		{
			parent = cur;
			cur = cur->_left;
		}
	}
	//判断是否找到了需要删除的节点
	if (cur == nullptr)
		return false;
	//删除
	//1.叶子
	if (cur->_left == nullptr&&cur->_right == nullptr)
	{
		if (cur == root)
		{
			//如果是根结点，更新根结点
			_root = nullptr;
		}
		else
		{
			if (parent->_left == cur)
				parent->_left = nullptr;
			else
				parent->_right = nullptr;

		}
		delete cur;
	}
	else if (cur->_left == nullptr)
	{
		//2，左孩子为空
		if (cur == _root)
		{
			_root = cur->_right;
		}
		else
		{
			if (parent->_left == cur)
				parent->_left = cur->_right;
			else
				parent->_right = cur->_right;
		}
	else if (cur->_right == nullptr)
	{
		//2.右孩子为空
		if (cur == _root)
		{
			_root = cur->_left;
		}
		else
		{
			if (parent->_left == cur)
				parent->_left = cur->_left;
			else
				parent->_left = cur->_left;
		}
		delete cur;
	}
	else
	{
		//4.左右孩子都存在
		//找最左或者最右节点
		//找右子树最左节点
		Node* leftMostChild = cur->_right;
		Node* parent = cur;
		while (leftMostChild->_left)
		{
			parent = leftMostChild;
			leftMostChild = leftMostChild->_left;
		}
		//值替换
		cur->_val = leftMostChild->_val;
		//删除最左或者最右节点
		paretn->_ = leftMostChild->_val;
		delete leftMostChild;
	}
	return true;
	}
	void inorder()
	{
		_inorder(_root);
		cout << endl;
	}
	void _inorder(Node* root)
	{
		if (root)
		{
			_inorder(root > _left)
				cout << cur->_val << " ";
			_inorder(root->_right);
		}
	}
	void destory(Node* root)
	{
		if (root)
		{
			destory(root->_left);
			destory(root->_right);
			delete root;
		}
	}
	~BSTree()
	{
		destory(_root);
	}

	void copyTree(Node* root)
	{
		if (root)
		{
			insert(root->_val);
			copyTree(root->_left);
			copy(root->_right);
		}
	}
	
	Node* copyTree2(Node* root)
	{
		if (root)
		{
			Node* cur = new Node(root->_val);
			cur->_left = copyTree(root->_left);
			cur->_right = copyTree(root->_right);
			return cur;
		}
		return nullptr;
	}
	BSTree()
		: _root(nullptr)
	{

	}

	BSTree(const BSTree& bst)
	{
		copyTree(bst._root);
	}
private:
	Node* _root = nullptr;
}

};

void test()
{
	BSTree bst;
}