Flatten Binary Tree to Linked List
Oct 14 '12
7105 / 21371
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
其实就是前序遍历,还可以考虑非递归的方式
/**
* Definition for binary tree
* public class TreeNode {
* int val;
* TreeNode left;
* TreeNode right;
* TreeNode(int x) { val = x; }
* }
*/
public class Solution {
public void flatten(TreeNode root) {
if(root ==null) return;
find(root);
}
public TreeNode find(TreeNode root){
if(root==null) return null;
TreeNode last =null;
TreeNode left = root.left,right = root.right;
if(root.left==null && root.right==null) return root;
if(root.left!=null){
root.right = left;
root.left = null;
last = find(left);
last.right = right;
}
if(right!=null)
last = find(right);
return last;
}
}