(java)leetcode Invert Binary Tree

Invert a binary tree.

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

to

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

Trivia:

This problem was inspired by this
original tweet by Max
Howell:

Google: 90% of our engineers use the software you wrote (Homebrew), but you can’t invert a binary tree on a whiteboard so fuck off.

思路：普通的递归题目，就是把左右节点对称的进行交换

代码如下(已通过leetcode)

/**

* 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;

TreeNode temp=root.left;

root.left=invertTree(root.right);

root.right=invertTree(temp);

return root;

}

}