【剑指offer 面试题27】二叉搜索树与双向链表

　　输入一颗二叉搜索树，将该二叉搜索树转换成一个排序的双向链表。

C++:

 #include <iostream>
 using namespace std;

 struct TreeNode
 {
     int val;
     TreeNode *left;
     TreeNode *right;
     TreeNode(int x = ):val(x), left(NULL), right(NULL){}
 };

 void ConvertNode(TreeNode *pNode, TreeNode **pLastNode)
 {
     if(pNode == )
         return ;

     if(pNode->left != )
         ConvertNode(pNode->left, pLastNode);

     pNode->left = (*pLastNode);
     if((*pLastNode) != )
         (*pLastNode)->right = pNode;
     (*pLastNode) = pNode;

     if(pNode->right != )
         ConvertNode(pNode->right, pLastNode);
 }

 int main()
 {
     TreeNode *root = new TreeNode();
     TreeNode *node6 = new TreeNode();
     TreeNode *node14 = new TreeNode();
     TreeNode *node4 = new TreeNode();
     TreeNode *node8 = new TreeNode();
     TreeNode *node12 = new TreeNode();
     TreeNode *node16 = new TreeNode();

     root->left = node6;
     root->right = node14;
     node6->left = node4;
     node6->right = node8;
     node14->left = node12;
     node14->right = node16;

     TreeNode *pLastNode = NULL;
     ConvertNode(root, &pLastNode);

     while(pLastNode != )
     {
         cout<<pLastNode->val<<" ";
         pLastNode = pLastNode->left;
     }
 }