LeetCode 226

Invert Binary Tree

Invert a binary tree.

     4
   /   \
  2     7
 / \   / \
1   3 6   9

to

     4
   /   \
  7     2
 / \   / \
9   6 3   1

 /**
  * Definition for a binary tree node.
  * public class TreeNode {
  *     int val;
  *     TreeNode left;
  *     TreeNode right;
  *     TreeNode(int x) { val = x; }
  * }
  */
 public class Solution {
     public TreeNode invertTree(TreeNode root) {
         if(root == null){
             return root;
         }else{
             TreeNode n = root.left;
             root.left = invertTree(root.right);
             root.right = invertTree(n);
             return root;
         }
     }
 }