翻转一棵二叉树。示例：输入：4/   \2     7/ \   / \
1   3 6   9
输出：4/   \7     2/ \   / \
9   6 3   1

代码

/*** Definition for a binary tree node.* public class TreeNode {*     int val;*     TreeNode left;*     TreeNode right;*     TreeNode(int x) { val = x; }* }*/
class Solution {public TreeNode invertTree(TreeNode root) {getInvertTree(root);return root;}public void getInvertTree(TreeNode root) {if(root==null) return;TreeNode temp=root.left;root.left=root.right;root.right=temp;//交换左右节点getInvertTree(root.left);//递归子节点getInvertTree(root.right);}
}