//肯定是要用中序遍歷。。。可是開始不怎麽會弄 
//為什麽這麽菜

/*
struct TreeNode {
    int val;
    struct TreeNode *left;
    struct TreeNode *right;
    TreeNode(int x) :
            val(x), left(NULL), right(NULL) {
    }
};*/
class Solution {
public:
    void ConvertSup(TreeNode* &proot,TreeNode* &pre)
    {
        ConvertSup(proot
 
->left,pre);
        
        proot->left=pre;
        if(pre!=NULL) pre->right=proot;
        pre=proot;
        
        ConvertSup(proot->right,pre);
    }
    
    TreeNode* Convert(TreeNode* pRootOfTree)
    {
        TreeNode* pre=NULL;
        if(pRootOfTree==NULL)
        {
            
 
return NULL;
        }
        ConvertSup(pRootOfTree,pre);
        
        TreeNode* cur=pRootOfTree;
        while(cur->left!=NULL)
        {
            cur=cur->left;
        }
        
        return cur;
    }
};

劍指offer---二叉樹和雙向鏈表