N ary tree preorder traversal

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76.7% acceptance

Jan 13, 2026

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

Solution

C++

Time O(n)

Space O(1)

LeetCode

solution.cpp

class Solution {
public:
  vector<int> preorder(Node* root) {
    if (!root) return {};
    vector<int> result = {root->val};
    for (Node* child : root->children) {
      auto sub = preorder(child);
      result.insert(result.end(), sub.begin(), sub.end());
    }
    return result;
  }
};