[Leetcode] Flatten Binary Tree to Linked List (Java)

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

根据上述规律转换二叉树

递归把左子树放到右子树，并将原来右子树放到原来左子树的最右儿子上

public class Solution {
public void flatten(TreeNode root) {
if(root==null)
return;
TreeNode left = root.left;
TreeNode right = root.right;
if(left!=null){
flatten(root.left);
root.right = left;
root.left = null;
TreeNode cur = root.right;
while(cur.right!=null)
cur = cur.right;
cur.right = right;
}
if(right!=null)
flatten(right);
}
}