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。

 

/*
struct TreeNode {
    int val;
    struct TreeNode *left;
    struct TreeNode *right;
    TreeNode(int x) :
            val(x), left(NULL), right(NULL) {
    }
};*/
class Solution {
public:
    std::vector<TreeNode*> vv;
    void inorder(TreeNode* root)
    {
        if (root ->left != NULL)
        {
            inorder(root->left);
        }
        vv.push_back(root);
        if(root->right != NULL)
        {
            inorder(root->right);
        }
    }
    TreeNode* Convert(TreeNode* pRootOfTree)
    {
        if (pRootOfTree == NULL)
            return NULL;
        inorder(pRootOfTree);

        if(vv.size() == 1)
            return pRootOfTree;

        vv[0]->left = NULL;
        vv[0]->right = vv[1];
        int i = 1;
        for (i; i <= vv.size() - 2; ++i)
        {
            vv[i]->left = vv[i-1];
            vv[i]->right = vv[i+1];
        }
        vv[i]->left = vv[i-1];
        vv[i]->right = NULL;
        return vv[0];
    }
};