LintCode 翻转二叉树

题目描述：
翻转一棵二叉树

您在真实的面试中是否遇到过这个题？ Yes
样例
1 1
/ \ / \
2 3 => 3 2
/ \
4 4

思路分析：

交换左右子树。

ac代码：

/** * Definition of TreeNode: * class TreeNode { * public: *     int val; *     TreeNode *left, *right; *     TreeNode(int val) { *         this->val = val; *         this->left = this->right = NULL; *     } * } */class Solution {public:    /**     * @param root: a TreeNode, the root of the binary tree     * @return: nothing     */    void invertBinaryTree(TreeNode *root) {        // write your code here        if(!root)            return ;        invertBinaryTree(root->left);        invertBinaryTree(root->right);        swap(root->left,root->right);    }};