[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

Hints:

IF you notice carefully in the flattened tree, each node's right child points to the next node of a pre-order traversal.

The problem is to "flatten" a binary tree and convert it to a two-prong tree with only the right sub-tree (except for leaf nodes) at each node. It can be seen from the example of the observation topic that, on the basis of subsequent traversal, the Zuozi of a node is inserted between the nodes and the right sub-tree. Recursive implementation is simple.

Put the following code:

/**
 * Definition for binary tree
 * 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)
			return;
		Flatten (root->left);
		Flatten (root->right);
		treenode* p = root->right;
		Root->right = root->left;
		treenode* temp = root;
		Root->left = NULL;
		while (temp->right)
			temp = temp->right;
		Temp->right = P;
	}
};