n-ary-tree-preorder-traversal.cpp

/*
// Definition for a Node.
class Node {
public:
    int val;
    vector<Node*> children;

    Node() {}

    Node(int _val) {
        val = _val;
    }

    Node(int _val, vector<Node*> _children) {
        val = _val;
        children = _children;
    }
};
*/

class Solution {
    vector<int> pre;
public:
    void dfs(Node* root){
        if(root == NULL)
            return;
        pre.push_back(root->val);
        for(auto x: root->children){
            dfs(x);
        }        
    }
    vector<int> preorder(Node* root) {
        dfs(root);
        return pre;
    }
};