Invert a binary tree.
4
/
2 7
/ \ /
1 3 6 9
to
4
/
7 2
/ \ /
9 6 3 1
Solution:
/**
* 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;
TreeNode invertLeft = invertTree(root.left);
TreeNode invertRight = invertTree(root.right);
root.left = invertRight;
root.right = invertLeft;
return root;
}
}