leetcode 226. Invert Binary Tree

leetcode 226. Invert Binary Tree

题目

Total Accepted: 76777 Total Submissions: 172853 Difficulty: Easy
Invert a binary tree.

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

to

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

答案

 /**
  * 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==NULL)
            return NULL;    

        TreeNode* ptmpNode=root->left;  //临时的交换变量

        root->left=invertTree(root->right);
        root->right=invertTree(ptmpNode);

        return root;        
    }
};