题目：
二叉搜索树与双向链表
题目描述：
输入一棵二叉搜索树，将该二叉搜索树转换成一个排序的双向链表。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。
解题：
/*
struct TreeNode {
int val;
struct TreeNode *left;
struct TreeNode *right;
TreeNode(int x) :
val(x), left(NULL), right(NULL) {
}
};*/
class Solution {
public:
TreeNode* Convert(TreeNode* pRootOfTree)
{
stack<TreeNode *> s;
TreeNode *node = pRootOfTree;
TreeNode *root = NULL, *last = NULL;
while(node || s.size()){
while(node){
s.push(node);
node = node->left;
}
node = s.top();
s.pop();
if(root == NULL){
root = node;
last = node;
}else{
last->right = node;
node->left = last;
last = node;
}
node = node->right;
}
return root;
}
};
