Today I have done leetcode's September LeetCoding Challenge with cpp.

September LeetCoding Challenge 5

Description

N-ary Tree Level Order Traversal

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

Nary-Tree input serialization is represented in their level order traversal, each group of children is separated by the null value (See examples).

Example 1:

Input: root = [1,null,3,2,4,null,5,6]
Output: [[1],[3,2,4],[5,6]]

Example 2:

Input: root = [1,null,2,3,4,5,null,null,6,7,null,8,null,9,10,null,null,11,null,12,null,13,null,null,14]
Output: [[1],[2,3,4,5],[6,7,8,9,10],[11,12,13],[14]]

Constraints:

• The height of the n-ary tree is less than or equal to 1000
• The total number of nodes is between [0, 10^4]

Solution

auto speedup = [](){
  cin.tie(nullptr);
  cout.tie(nullptr);
  ios::sync_with_stdio(false);
  return 0;
}();
class Solution {
public:
  vector<vector<int>> levelOrder(Node* root) {
    if(!root) return {};
    vector<vector<int>> answer;
    queue<Node*> q;
    q.push(root);
    while(q.size()) {
      int sz = q.size();
      vector<int> level;
      for(int _ = 0; _ < sz; ++_) {
        auto cur = q.front();
        q.pop();
        level.push_back(cur->val);
        for(auto child : cur->children) {
          q.push(child);
        }
      }
      answer.push_back(level);
    }
    return answer;
  }
};

// Accepted
// 38/38 cases passed (20 ms)
// Your runtime beats 86.78 % of cpp submissions
// Your memory usage beats 34.23 % of cpp submissions (11.9 MB)