#pragma once
#include<iostream>
enum Colour
{
	RED,
	BLACK
};
template<class K,class V>
class RBTreeNode
{
public:
	RBTreeNode(const std::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;
	std::pair<K, V> _kv;
	Colour _col;
};

template<class K,class V>
class RBTree
{
public:
	typedef RBTreeNode<K, V> Node;
	RBTree()
		:_root(nullptr)
	{

	}
	bool insert(const std::pair<K,V> &kv)
	{
		if (_root == nullptr)
		{
			_root = new Node(kv);
			_root->_col = BLACK;
			return true;
		}
		Node* parent = nullptr;
		Node* cur = _root;
		while (cur != nullptr)
		{
			if (kv.first > cur->_kv.first)
			{
				parent = cur;
				cur = cur->_right;
			}
			else if (kv.first < cur->_kv.first)
			{
				parent = cur;
				cur = cur->_left;
			}
			else
			{
				return false;
			}
		}
		//New node
		cur = new Node(kv);
		cur->_col = RED;
		if (kv.first > parent->_kv.first)
		{
			parent->_right = cur;
			cur->_parent = parent;
		}
		else
		{
			parent->_left = cur;
			cur->_parent = parent;
		}
		//Control balance
		while (parent != nullptr && parent->_col == RED)  //If the father exists and the father's node is red
		{
			Node* grandfather = parent->_parent;
			if (parent == grandfather->_left)
			{
				Node* uncle = grandfather->_right;
				//Case 1: the uncle node exists and the color of the uncle node is red
				if (uncle != nullptr && uncle->_col == RED)
				{
					parent->_col = uncle->_col = BLACK;  //The father node and uncle node turn black
					grandfather->_col = RED;
					
					//grandfather may not be the root node. Continue to update
					cur = grandfather;
					parent = cur->_parent;
				}
				else //Case 2 + 3, uncle does not exist / exists and is black, which may be caused by case 1 - > case 2 / case 3
				{
					//        g
					//      p
					//    c
					if (cur == parent->_left)   
					{
						//Right single rotation
						RotateR(grandfather);
						parent->_col = BLACK;
						grandfather->_col = RED;
					}
					else
					{
						//Trigger left and right double rotation
						RotateL(parent);
						RotateR(grandfather);
						cur->_col = BLACK;
						grandfather->_col = RED;
					}
					break;
				}
			}
			else
			{
				Node* uncle = grandfather->_left;
				//Case 1: Uncle exists and the color of uncle is red
				if (uncle != nullptr && uncle->_col == RED)
				{
					parent->_col = uncle->_col = BLACK;  //Uncle and father change color
					grandfather->_col = RED;

					//grandfather may not be the root node, so it may be updated upward all the time
					cur = grandfather;
					parent = cur->_parent;
				}
				else  //Case 2 + 3, uncle does not exist / exists and is black
				{
					if (cur == parent->_right)  //Trigger left rotation
					{
						RotateL(grandfather);
						parent->_col = BLACK;
						grandfather->_col = RED;
					}
					else  
					{
						//Trigger right left double rotation
						RotateR(parent);
						RotateL(grandfather);
						grandfather->_col = RED;
						cur->_col = BLACK;
					}
					break;
				}
			}
		}
		_root->_col = BLACK;
		return true;
	}
private:
	void RotateR(Node* parent)
	{
		Node* subL = parent->_left;
		Node* subLR = subL->_right;
		Node* parentparent = parent->_parent;

		parent->_left = subLR;
		if (subLR != nullptr)
		{
			subLR->_parent = parent;
		}
		subL->_right = parent;
		parent->_parent = subL;
		if (_root == parent)
		{
			_root = subL;
			subL->_parent = nullptr;
		}
		else
		{
			if (parentparent->_left == parent)
				parentparent->_left = subL;
			else
				parentparent->_right = subL;
			subL->_parent = parentparent;
		}
	}
	void RotateL(Node* parent)
	{
		
		Node* subR = parent->_right;
		Node* subRL = subR->_left;
		Node* parentparent = parent->_parent;

		parent->_right = subRL;
		if (subRL != nullptr)
			subRL->_parent = parent;

		subR->_left = parent;
		parent->_parent = subR;
		if (parent == _root)
		{
			_root = subR;
			subR->_parent = nullptr;
		}
		else
		{
			if (parentparent->_left == parent)
				parentparent->_left = subR;
			else
				parentparent->_right = subR;

			subR->_parent = parentparent;
		}
	}
public:
	void inoder()
	{
		Node* cur = _root;
		Node* MostRight = nullptr;
		while (cur != nullptr)
		{
			MostRight = cur->_left;
			if (MostRight != nullptr)
			{
				while (MostRight->_right != nullptr && MostRight->_right != cur)
				{
					MostRight = MostRight->_right;
				}
				if (MostRight->_right == nullptr)
				{
					MostRight->_right = cur;
					cur = cur->_left;
					continue;
				}
				else
				{
					MostRight->_right = nullptr;
				}
			}
			std::cout << cur->_kv.first << ":" << cur->_kv.second << std::endl;
			cur = cur->_right;
		}
	}
	bool IsBalance()
	{
		if (_root && _root->_col == RED)
		{
			std::cout << "The root node is not black" << std::endl;
			return false;
		}

		// The number of black nodes in the leftmost path is used as the reference value
		int banchmark = 0;
		Node* left = _root;
		while (left)
		{
			if (left->_col == BLACK)
				++banchmark;

			left = left->_left;
		}

		int blackNum = 0;
		return _IsBalance(_root, banchmark, blackNum);
	}

	bool _IsBalance(Node* root, int banchmark, int blackNum)
	{
		if (root == nullptr)
		{
			if (banchmark != blackNum)
			{
				std::cout << "There is an unequal number of black nodes in the path" << std::endl;
				return false;
			}

			return true;
		}

		if (root->_col == RED && root->_parent->_col == RED)
		{
			std::cout << "Continuous red nodes appear" << std::endl;
			return false;
		}

		if (root->_col == BLACK)
		{
			++blackNum;
		}

		return _IsBalance(root->_left, banchmark, blackNum)
			&& _IsBalance(root->_right, banchmark, blackNum);
	}
private:
	Node* _root;
};

test.cpp

#include"AVL.h"
#include"RBTree.h"

void AVLTreeTest(void)
{
	AVLTree<int, int> av;
	int array[] = { 9,6,4,3,7,3,2,0,544,43224,23,423,42,4234,2,4242,423,42,7,11,98,5 };
	for (const auto& e : array)
	{
		av.insert(std::pair<int,int>(e,e));
	}
	av.inoder();
}
void RBTreeTest(void)
{
	RBTree<int, int> rb;
	int array[] = { 9,6,4,3,7,3,2,0,544,43224,23,423,42,4234,2,4242,423,42,7,11,98,5 };
	for (const auto& e : array)
	{
		rb.insert(std::pair<int, int>(e, e));
		std::cout << rb.IsBalance() << std::endl;
	}
	rb.inoder();
}
int main()
{
	//AVLTreeTest();
	RBTreeTest();
}