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 should 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.

Solution:

 1 /**
 2  * Definition for binary tree
 3  * public class TreeNode {
 4  *     int val;
 5  *     TreeNode left;
 6  *     TreeNode right;
 7  *     TreeNode(int x) { val = x; }
 8  * }
 9  */
10 public class Solution {
11     public void flatten(TreeNode root) {
12         // Start typing your Java solution below
13         // DO NOT write main() function
14         //solve1(root);
15         if(root == null) return;
16         if(root.left != null){
17             TreeNode left = root.left;
18             TreeNode right = root.right;
19             root.left = null;
20             root.right = left;
21             TreeNode rightMost = root.right;
22             while(rightMost.right != null){
23                 rightMost = rightMost.right;
24             }
25             rightMost.right = right;
26         }
27         flatten(root.right);
28     }
29 }

 

posted @ 2013-01-27 12:48  cradle  阅读(1392)  评论(0)    收藏  举报