n-ary-tree-preorder-traversal

N-ary Tree Preorder Traversal – LeetCode 589

Problem

Description

Given an n-ary tree, return the preorder traversal of its nodes’ values.

Answer

Original

Code

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

    Node() {}

    Node(int _val, vector<Node*> _children) {
        val = _val;
        children = _children;
    }
};
*/
class Solution {
private:
    vector<int> ans;
    
    void recursive(Node *root){
        if(root){
            ans.emplace_back(root->val);
            for(auto &i : root->children)
                recursive(i);
        }
    }
public:
    vector<int> preorder(Node* root) {
        recursive(root);
        return ans;
    }
};

思路

简单的遍历。时间复杂度$O(n)$，空间复杂度$O(n)$。
耗时$44$ ms，排名$1.34\%$

Better

思路

还没看到更好的思路。