中序遍历
/**
* Definition for a binary tree node.
* struct TreeNode {
* int val;
* TreeNode *left;
* TreeNode *right;
* TreeNode(int x) : val(x), left(NULL), right(NULL) {}
* };
*/
class Solution {
public:
TreeNode* pre=new TreeNode(0x80000000),*p1=NULL,*p2=NULL;
void In_Traver(TreeNode* root){
if(root->left) In_Traver(root->left);
if(root->val<pre->val && !p1) p1=pre;
if(p1 && root->val<p1->