Binary Tree Inorder Traversal

/**
 * 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:
    vector<int> inorderTraversal(TreeNode* root) {
        vector<int> v;
        if(root==NULL) return v;
        if(root->left==NULL && root->right==NULL) {
            v.push_back(root->val);
            return v;
        }

        if(root->left)
             v=inorderTraversal(root->left);

        v.push_back(root->val);

         if(root->right){
             vector<int> vv;
             vv=inorderTraversal(root->right); 
             for(int i=0;i<vv.size();i++){
                 v.push_back(vv[i]);
             }
         }
         return v;
    }
};