红黑树 模拟

红黑树 模拟

#pragma once
#include 
enum Color
{
	RED,
	BLACK
};

template <typename K, typename V>
struct RBTreeNode
{
	RBTreeNode(const pair<K, V>& kv)
		:_left(nullptr)
		,_right(nullptr)
		,_parent(nullptr)
		,_kv(kv)
		,_col(RED)
	{}
	RBTreeNode<K, V>* _left;
	RBTreeNode<K, V>* _right;
	RBTreeNode<K, V>* _parent;
	pair<K, V> _kv;
	Color _col;
};


template <typename K, typename V>
class RBTree
{
	typedef RBTreeNode<K, V> Node;
public:
	void RotateL(Node* parent)
	{
		Node* cur = parent->_right;
		Node* grandparent = parent->_parent;
		/*修改链接关系*/
		//grandparent
		if (parent == _root)
		{
			_root = cur;
		}
		else
		{
			if (grandparent->_left == parent)
			{
				grandparent->_left = cur;
			}
			else
			{
				grandparent->_right = cur;
			}
		}
		//cur左子树头节点
		if (cur->_left != nullptr)
		{
			cur->_left->_parent = parent;
		}
		//parent
		parent->_parent = cur;
		parent->_right = cur->_left;
		//cur
		cur->_left = parent;
		cur->_parent = grandparent;
	}
	void RotateR(Node* parent)
	{
		Node* cur = parent->_left;
		Node* grandparent = parent->_parent;
		/*修改链接关系*/
		//grandparent
		if (parent == _root)
		{
			_root = cur;
		}
		else
		{
			if (grandparent->_left == parent)
			{
				grandparent->_left = cur;
			}
			else
			{
				grandparent->_right = cur;
			}
		}
		//cur右子树头节点
		if (cur->_right != nullptr)
		{
			cur->_right->_parent = parent;
		}
		//parent
		parent->_parent = cur;
		parent->_left = cur->_right;
		//cur
		cur->_parent = grandparent;
		cur->_right = parent;
	}
	void RotateLR(Node* parent)
	{
		Node* cur = parent->_left;
		RotateL(cur);
		RotateR(parent);
	}
	void RotateRL(Node* parent)
	{
		Node* cur = parent->_right;
		RotateR(cur);
		RotateL(parent);
	}
	
	bool Insert(const pair<K, V>& kv)
	{
		if (_root == nullptr)
		{
			_root = new Node(kv);
			_root->_col = BLACK;
			return true;
		}
		Node* cur = _root;
		Node* parent = nullptr;
		while (cur != nullptr)
		{
			if (kv.first < (cur->_kv).first)
			{
				parent = cur;
				cur = cur->_left;
			}
			else if (kv.first > (cur->_kv).first)
			{
				parent = cur;
				cur = cur->_right;
			}
			else
			{
				return false;
			}
		}
		Node* newnode = new Node(kv);
		cur = newnode;
		if (kv.first < (parent->_kv).first)
		{
			newnode->_parent = parent;
			parent->_left = newnode;
		}
		else if (kv.first > (parent->_kv).first)
		{
			newnode->_parent = parent;
			parent->_right = newnode;
		}

		while (parent != nullptr)
		{
			Node* grandparent = parent->_parent;
			if (grandparent == nullptr)
			{
				parent->_col = BLACK;
				_root = parent;
				break;
			}
			else if (parent->_col == BLACK)
			{
				break;
			}
			else if (parent->_col == RED)
			{
				if (grandparent->_left == parent && grandparent->_right == nullptr)  // 1
				{
					if (parent->_left == cur)
					{
						RotateR(grandparent);
						parent->_col = RED;
						grandparent->_col = BLACK;
						cur->_col = BLACK;

						cur = parent;
						parent = parent->_parent;
					}
					else
					{
						RotateLR(grandparent);
						cur->_col = RED;
						grandparent->_col = BLACK;
						parent->_col = BLACK;

						parent = cur->_parent;
					}
				}
				else if (grandparent->_right == parent && grandparent->_left == nullptr) // 1
				{
					if (parent->_left == cur)
					{
						RotateRL(grandparent);
						cur->_col = RED;
						grandparent->_col = BLACK;
						parent->_col = BLACK;

						parent = cur->_parent;
					}
					else
					{
						RotateL(grandparent);
						parent->_col = RED;
						grandparent->_col = BLACK;
						cur->_col = BLACK;

						cur = parent;
						parent = parent->_parent;
					}
				}
				else if (grandparent->_left->_col == RED && grandparent->_right->_col == RED)  // 1 
				{
					grandparent->_col = RED;
					grandparent->_left->_col = BLACK;
					grandparent->_right->_col = BLACK;

					cur = grandparent;
					parent = grandparent->_parent;
				}
				else if (grandparent->_left == parent && grandparent->_right->_col == BLACK)
				{
					if (parent->_left == cur)
					{
						RotateR(grandparent);
						parent->_col = BLACK;
						grandparent->_col = RED;
					}
					else
					{
						RotateLR(grandparent);
						cur->_col = BLACK;
						grandparent->_col = RED;
					}
					break;
				}
				else if (grandparent->_right == parent && grandparent->_left->_col == BLACK)
				{
					if (parent->_left == cur)
					{
						RotateRL(grandparent);
						cur->_col = BLACK;
						grandparent->_col = RED;
					}
					else
					{
						RotateL(grandparent);
						parent->_col = BLACK;
						grandparent->_col = RED;
					}
					break;
				}
			}
		}
		if (_root->_col == RED)
		{
			_root->_col = BLACK;
		}
		return true;
	}

	int GetBlackCount()
	{
		int blackcount = 0;
		Node* cur = _root;
		while (cur != nullptr)
		{
			if (cur->_col == BLACK)
			{
				blackcount++;
			}
			cur = cur->_left;
		}
		return blackcount;
	}

	bool IsRBTree()
	{
		if (_root == nullptr)
		{
			return true;
		}
		if (_root->_col == RED)  //性质一
		{
			return false;
		}
		int blackcount = GetBlackCount();
		return _IsRBTree(_root, 0, blackcount);
	}
private:
	bool _IsRBTree(Node* root, int nowBlackCount, const int blackcount)
	{
		if (root == nullptr)
		{
			if (nowBlackCount == blackcount)
			{
				return true;
			}
			else
			{
				return false;
			}
		}
		if (root->_col == BLACK)
		{
			nowBlackCount++;
		}
		else if (root->_col == RED)
		{
			if (root->_left != nullptr && root->_left->_col == RED)
			{
				return false;
			}
			if (root->_right != nullptr && root->_right->_col == RED)
			{
				return false;
			}
		}
		return _IsRBTree(root->_left, nowBlackCount, blackcount) && _IsRBTree(root->_right, nowBlackCount, blackcount);
	}
	Node* _root = nullptr;
};