leetcode

0 class Solution {

1 public:

2 vector<int> preorder(Node *root) {

3 if (!root) return {};

4 vector<int> res;

5 stack<Node *> st;

6 st.push(root);

7 while (!st.empty()) {

8 Node *root = st.top();

9 st.pop();

10 res.push_back(root->val);

11 reverse(root->children.begin(), root->children.end());

12 for (Node *c : root->children)

13 st.push(c);

14 }

15 return res;

16 }

17 };