37-Invert Binary Tree

1. Invert Binary Tree My Submissions QuestionEditorial Solution
   Total Accepted: 87818 Total Submissions: 193396 Difficulty: Easy
   Invert a binary tree.

   4
   / \
   2 7
   / \ / \
   1 3 6 9
   to
   4
   / \
   7 2
   / \ / \
   9 6 3 1
   逆转一颗二叉树
   思路：so easy

/**
 * 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 *tnode;
        tnode = root->left;
        root->left = root->right;
        root->right = tnode;
        invertTree(root->left);
        invertTree(root->right);
        return root;
    }
};