剑指 Offer 27. 二叉树的镜像

同LeetCode226翻转二叉树

class Solution {
public:
    TreeNode* mirrorTree(TreeNode* root) {
        if(root == NULL) return NULL;
        TreeNode* node = root->left;
        root->left = root->right; root->right = node;
        mirrorTree(root->left);
        mirrorTree(root->right);
        return root;
    }
};