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 null; } if(root.left==null && root.right==null){ return root; } TreeNode temp=root.left; root.left=invertTree(root.right); root.right=invertTree(temp); return root; } }