Invert Binary Tree(easy)

1.直接把递归把左右子树翻转即可

AC代码：

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

    }
    TreeNode* invertTree(TreeNode* root) {
            invert(root);
            return root;
    }

};