[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

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題解：

code:

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