LeetCode_invert binary tree

原题链接：https://leetcode.com/problems/invert-binary-tree/

/**
* 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) {
invert(root);
return root;
}
void invert(TreeNode* root)
{
if(!root)
return;
invert(root->left);
invert(root->right);
swap(root->left,root->right);
}
};