【leetcode】Binary Tree Postorder Traversal

 1 class Solution {
 2 public:
 3     vector<int> postorderTraversal(TreeNode *root) {
 4         vector<int> out;
 5         stack<TreeNode*> s;
 6         TreeNode* node=root;
 7         s.push(node);
 8         while(!s.empty()&&node){
 9             node=s.top();
10             out.push_back(node->val);
11             s.pop();
12             if(node->left) s.push(node->left);
13             if(node->right) s.push(node->right);
14         }
15         
16         reverse(out.begin(),out.end());
17         return out;
18     }
19 };