27 二叉搜索树与双向链表

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。

 

 

C++:

/*
struct TreeNode {
    int val;
    struct TreeNode *left;
    struct TreeNode *right;
    TreeNode(int x) :
            val(x), left(NULL), right(NULL) {
    }
};*/
class Solution {
private:
    TreeNode* pre = NULL ;
    TreeNode* head = NULL ;
public:
    TreeNode* Convert(TreeNode* pRootOfTree)
    {
        if (pRootOfTree == NULL)
            return NULL ;
        InOrder(pRootOfTree) ;
        return head ;
    }
    
    void InOrder(TreeNode* node){
        if (node == NULL)
            return ;
        InOrder(node->left) ;
        node->left = pre ;
        if (pre != NULL){
            pre->right = node ;
        }
        pre = node ;
        if (head == NULL ){
            head = node ;
        }
        InOrder(node->right) ;
    }
};