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

Hints:

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

Original question link: https://oj.leetcode.com/problems/flatten-binary-tree-to-linked-list/

Question: Given a binary tree, it is flushed into a chain table by the prefix.

Idea: recursive processing. Place the right subtree behind the left subtree and clear the left subtree.

public void flatten(TreeNode root) {if(root == null)return;flatten(root.left);flatten(root.right);TreeNode tmp = root;if(tmp.left == null)return;elsetmp = tmp.left;while(tmp.right != null)tmp = tmp.right;tmp.right = root.right;root.right = root.left;root.left = null;}    // Definition for binary tree    public class TreeNode {        int val;        TreeNode left;        TreeNode right;        TreeNode(int x) { val = x; }    }

The same method, but not recursion.

public void flatten(TreeNode root){while(root != null){if(root.left != null){TreeNode tmp = root.left;while(tmp.right != null)tmp = tmp.right;tmp.right = root.right;root.right = root.left;root.left = null;}root = root.right;}}

Reference: http://blog.csdn.net/perfect8886/article/details/20000083

Leetcode -- flatten binary tree to linked list