[LeetCode 解题报告]114. Flatten Binary Tree to Linked List

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

For example, given the following tree:

    1
   / \
  2   5
 / \   \
3   4   6

The flattened tree should look like:

1
 \
  2
   \
    3
     \
      4
       \
        5
         \
          6

考察：将二叉树转换为右子树；

/**
 * 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) {
        
        if (root == NULL)
            return ;
        if (root->left)
            flatten(root->left);
        if (root->right)
            flatten(root->right);
        
        TreeNode *cur = root->right;
        root->right = root->left;
        root->left = NULL;
        while(root->right)
            root = root->right;
        root->right = cur;
    }
}