1、将二叉搜索树转换成一个排序的双向链表。提示：要求不能创建任何新的结点，只能调整树中结点指针的指向，也就是left当prev，right当next。--中序线索化的变型。 

	Node* BSTreeToList()  {if(_pRoot == NULL)  return NULL;  Node* pHead = _pRoot;//找到最左边的结点，即转换后链表的头结点while(pHead->_pleft != NULL)pHead = pHead->_pleft; Node* prev = NULL;  //进行转换  _BSTreeToList(_pRoot, prev);  return pHead;  }void _BSTreeToList(Node*& pRoot, Node*& prev){if(pRoot){_BSTreeToList(pRoot->_pleft, prev);pRoot->_pleft = prev;//链表的左孩子指向上一个节点if(prev && prev->_pright == NULL)prev->_pright = pRoot;prev = pRoot;if(NULL != pRoot->_pright)_BSTreeToList(pRoot->_pright, prev);}}

完整代码：

#include<iostream>
#include<utility>
using namespace std;template<class K, class V>
struct BinarySearchTreeNode
{BinarySearchTreeNode<K, V>*_pleft;BinarySearchTreeNode<K, V>*_pright;K _key;V _value;BinarySearchTreeNode(const K& key, const V& value):_pleft(NULL), _pright(NULL), _key(key),_value(value){}
};template<class K, class V>
class BinarySearchTree
{typedef BinarySearchTreeNode<K, V> Node;
public:BinarySearchTree():_pRoot(NULL){}BinarySearchTree(const BinarySearchTree<K, V>& tree):_pRoot(NULL){_pRoot = _CopyBSTree(tree._pRoot);}Node& operator=(Node& tree){if (this != &tree){BinarySearchTree<K, V> tmp(tree);swap(_pRoot, tmp._pRoot);}return *this;}~BinarySearchTree(){_Destory(_pRoot);}  //插入（非递归）bool Insert(const K& key, const V& value){if (_pRoot == NULL){_pRoot = new Node(key, value);return true;}Node* pCur = _pRoot;Node* pParent = NULL;while (pCur){pParent = pCur;if (key < pCur->_key)pCur = pCur->_pleft;else if (key > pCur->_key)pCur = pCur->_pright;elsereturn false;}pCur = new Node(key, value);if (key < pParent->_key)pParent->_pleft = pCur;elsepParent->_pright = pCur;return true;}//插入（递归）bool Insert_R(const K& key, const V& value){return _Insert_R(_pRoot, key, value);}Node* Find(const K& key){if(NULL == _pRoot)return NULL;Node* pCur = _pRoot;while (pCur){if (key == pCur->_key)return pCur;if (key < pCur->_key)pCur = pCur->_pleft;elsepCur = pCur->_pright;}return NULL;}bool Remove(const K& key){Node* pCur = _pRoot;Node* pParent = NULL;while (pCur){if (key < pCur->_key){pParent = pCur;pCur = pCur->_pleft;}else if (key > pCur->_key){pParent = pCur;pCur = pCur->_pright;}elsebreak;}//跳出循环：pCur为空， 找到节点。//删除节点pCur: 1、只有左子树、左右子树都没有//			    2、只有右子树//			    3、左右孩子都有。if(NULL == pCur)//空树return false;if (pCur->_pright == NULL)//只有左子树或左右子树都没有{if (pCur == _pRoot){_pRoot = pCur->_pleft;}else{if (pParent->_pleft == pCur)pParent->_pleft = pCur->_pleft;elsepParent->_pright = pCur->_pleft;}delete pCur;}else if (pParent->_pleft == NULL)//只有右子树{if (pCur == _pRoot){_pRoot = pCur->_pright;}else{if (pParent->_pleft == pCur)pParent->_pleft = pCur->_pright;elsepParent->_pright = pCur->_pright;}delete pCur;}else//左右子树都不为空:找右子树最小节点（中序遍历的第一个节点）把值互换，删除找到的节点。{Node* firstInNode = pCur->_pright;pParent = pCur;while(firstInNode->_pleft){pParent =  firstInNode;firstInNode = firstInNode->_pleft;}pCur->_key = firstInNode->_key;pCur->_value = firstInNode->_value;if(firstInNode == pCur->_pright)pParent->_pright = firstInNode->_pright;elsepParent->_pleft = firstInNode->_pright;delete firstInNode;	}return true;}Node* BSTreeToList()  {if(_pRoot == NULL)  return NULL;  Node* pHead = _pRoot;//找到最左边的结点，即转换后链表的头结点while(pHead->_pleft != NULL)pHead = pHead->_pleft; Node* prev = NULL;  //进行转换  _BSTreeToList(_pRoot, prev);  return pHead;  }private:Node* _CopyBSTree(Node* pRoot){if (pRoot){Node* pNewRoot = new Node(pRoot->_key, pRoot->_value);pNewRoot->_pleft = _CopyBSTree(pRoot->_pleft);pNewRoot->_pright = _CopyBSTree(pRoot->_pright);return pNewRoot;}elsereturn NULL;}void _Insert_R(Node*& pRoot, const K& key, const V& value){if (_pRoot == NULL){_pRoot = new Node(key, value);return true;}if(key < pRoot->_key)return _Insert_R(pRoot->_pleft, key, value);else if(key > pRoot->_key)return _Insert_R(pRoot->_pright, key, value);elsereturn false;}void _Destory(Node* pRoot){if (_pRoot == NULL)return;_Destory(pRoot->_pleft);_Destory(pRoot->_pright);delete pRoot;}void _BSTreeToList(Node*& pRoot, Node*& prev){if(pRoot){_BSTreeToList(pRoot->_pleft, prev);pRoot->_pleft = prev;//链表的左孩子指向上一个节点if(prev && prev->_pright == NULL)prev->_pright = pRoot;prev = pRoot;if(NULL != pRoot->_pright)_BSTreeToList(pRoot->_pright, prev);}}
private:BinarySearchTreeNode<K, V>* _pRoot;
};int main()
{int a[] = { 5, 3, 4, 1, 7, 8, 2, 6, 0, 9 };BinarySearchTree<int, int> t;t.Insert(5,5);t.Insert(3,3);t.Insert(4,4);t.Insert(1,1);t.Insert(7,7);t.Insert(8,8);t.Insert(2,2);t.Insert(6,6);t.Insert(0,0);t.Insert(9,9);BinarySearchTreeNode<int, int>* list = t.BSTreeToList(); system("pause");return 0;
}