Leetcode#129 Sum Root to Leaf Numbers

 1 vector<int> path;
 2     
 3 int sumNumbers(TreeNode *root) {
 4         if (!root)
 5             return 0;
 6             
 7         int sum = 0;
 8         path.push_back(root->val);
 9         
10         if (!root->left && !root->right) {
11             for (int i = 0; i < path.size(); i++)
12                 sum = sum * 10 + path[i];
13         }
14         else {
15             if (root->left)
16                 sum += sumNumbers(root->left);
17             if (root->right)
18                 sum += sumNumbers(root->right);
19         }
20         
21         path.pop_back();
22         
23         return sum;
24 }