[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 shoshould look like:

   1         2             3                 4                     5                         6

 

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

Https://oj.leetcode.com/problems/flatten-binary-tree-to-linked-list/

The question must be traversed in the forward order and converted into a linked list.

Idea: implement the left and right subtree recursively, and then adjust the pointer to connect.

public class Solution {    public void flatten(TreeNode root) {        if (root == null)            return;        flatten(root.left);        flatten(root.right);        TreeNode p = root;        if (p.left == null)            return;        else            p = p.left;        while (p.right != null)            p = p.right;        p.right = root.right;        root.right = root.left;        root.left = null;    }    public static void main(String[] args) {        TreeNode root = new TreeNode(1);        root.left = new TreeNode(2);        root.left.left = new TreeNode(3);        root.left.right = new TreeNode(4);        root.right = new TreeNode(5);        root.right.right = new TreeNode(6);        new Solution().flatten(root);        ;    }}

View code

 

Refer:

Http://blog.csdn.net/havenoidea/article/details/11822019

Http://www.cnblogs.com/feiling/p/3278639.html