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 后序遍历，根节点在顶上，相当于把左右子树连好再加上根节点
/**
* Definition for a binary tree node.
* public class TreeNode {
* int val;
* TreeNode left;
* TreeNode right;
* TreeNode(int x) { val = x; }
* }
*/
public class Solution {
private TreeNode prev = null;
public void flatten(TreeNode root) {
if(root == null){
return;
}
flatten(root.left);
flatten(root.right);
root.right = prev;
root.left = null;
prev = root;
}
}
