二叉搜索树与双向链表

[guanpengchn]

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:
    TreeNode* Convert(TreeNode* root)
    {
        if(!root){
            return nullptr;
        }
        if(root->left==nullptr && root->right==nullptr){
            return root;
        }
        TreeNode* left=Convert(root->left);
        TreeNode* p = left;
        while(p && p->right){
            p = p->right;
        }
        if(left){
            p->right = root;
            root->left = p;
        }
        TreeNode* right = Convert(root->right);
        if(right){
            right->left = root;
            root->right = right;
        }
        return left==nullptr?root:left;
    }
};