LeetCode Binary Tree Upside Down

/**
* Definition for binary tree
* struct TreeNode {
*     int val;
*     TreeNode *left;
*     TreeNode *right;
*     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
* };
*/
class Solution {
public:
TreeNode *upsideDownBinaryTree(TreeNode *root) {
if(!root){
return NULL;
}
TreeNode *Left = NULL, *right = NULL;
while(root->left){
TreeNode *orginalLeft = root -> left;
TreeNode *orginalRight = root -> right;
root->left = Left;
root->right = right;
Left = orginalRight;
right = root;
root = orginalLeft;
}
root->left = Left;
root->right = right;
return root;
}
};