LeetCode 226 翻转二叉树

题目链接：https://leetcode-cn.com/problems/invert-binary-tree/

思路描述：递归法：翻转左右子树，然后对左右子树翻转。LeetCode代码如下：

/**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
 * };
 */
class Solution {
public:
    TreeNode* invertTree(TreeNode* root) {
         if(!root){
             return root;
         }
          if(!root->left&&!root->right){
              return root;
          }
      
          TreeNode* temp=root->left;//
          root->left=root->right;//
          root->right=temp;

          invertTree(root->left);
          invertTree(root->right);
          return root;
    }
};