線索二叉樹的插入與刪除

#pragma once

namespace Y{

	template <class T>
	class TreeNode
	{
		T m_data;
		TreeNode<T> * m_left;
		TreeNode<T> * m_right;
	public:
		TreeNode(const T & val = T()) :
			m_data(val),
			m_left(nullptr),
			m_right(nullptr)
		{}

		template <class T>
		friend class BinarySortTree;
	};

	template <class T>
	class BinarySortTree
	{
		TreeNode<T> * m_root;
	public:
		BinarySortTree() :
			m_root(nullptr)
		{}

		bool insert(const T &val)
		{
			if (m_root == nullptr)
			{
				m_root = new TreeNode<T>(val);
				return true;
			}

			TreeNode<T> * cur = m_root;
			TreeNode<T> * pre = nullptr;

			while (cur)
			{
				if (val < cur->m_data)
				{
					pre = cur;
					cur = cur->m_left;
				}
				else if (val > cur->m_data)
				{
					pre = cur;
					cur = cur->m_right;
				}
				else
				{
					return false;
				}
			}

			cur = new TreeNode<T>(val);
			if (val < pre->m_data)
			{
				pre->m_left = cur;
			}
			else
			{
				pre->m_right = cur;
			}

			return true;
		}

		bool erase(const T &val)
		{
			if (m_root == nullptr)
			{
				return false;
			}

			TreeNode<T> * cur = m_root;
			TreeNode<T> * pre = nullptr;

			while (cur)
			{
				if (val < cur->m_data)
				{
					pre = cur;
					cur = cur->m_left;
				}
				else if (val > cur->m_data)
				{
					pre = cur;
					cur = cur->m_right;
				}
				else
				{
					break;
				}
			}

			if (cur == nullptr)
			{
				return false;
			}

			if (cur->m_left && cur->m_right)
			{
				TreeNode<T> * cur2 = cur->m_left;
				TreeNode<T> * pre2 = cur;

				if (cur2->m_right)
				{
					for (; cur2->m_right; pre2 = cur2, cur2 = cur2->m_right);
					pre2->m_right = cur2->m_left;
					cur2->m_left = cur->m_left;
				}

				cur2->m_right = cur->m_right;

				if (cur->m_data < pre->m_data)
				{
					pre->m_left = cur2;
				}
				else
				{
					pre->m_right = cur2;
				}

				delete cur;
			}
			else if (cur->m_left)
			{
				if (cur->m_data < pre->m_data)
				{
					pre->m_left = cur->m_left;
				}
				else
				{
					pre->m_right = cur->m_left;
				}
				delete cur;
			}
			else
			{
				if (cur->m_data < pre->m_data)
				{
					pre->m_left = cur->m_right;
				}
				else
				{
					pre->m_right = cur->m_right;
				}
				delete cur;
			}

		}
	};

};

#include "binarySortTree.h"
#include <iostream>
using namespace std;

int main()
{
	Y::BinarySortTree<int> bst;

	bst.insert(5);
	bst.insert(3);
	bst.insert(8);
	bst.insert(6);
	bst.insert(4);
	bst.insert(7);
	bst.insert(1);
	bst.insert(2);

	bst.erase(2);

	return 0;
}