Leetcode Flatten Binary Tree to Linked List

Given a binary tree, flatten it to a linked list in-place.

For example,
Given

         1        / \       2   5      / \   \     3   4   6

The flattened tree should look like:

   1    \     2      \       3        \         4          \           5            \             6

关键在原来的树上，如何进行变换而且不影响继续遍历。

代码如下：

/** * 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:    void flatten(TreeNode* root) {        TreeNode* now = root;        while(now)        {            if(now->left)            {                TreeNode* pre = now->left;                while(pre->right != NULL)                    pre = pre->right;                pre->right = now->right;                now->right = now->left;                now->left = NULL;            }            now = now->right;        }    }};