N-Ary Tree Level Order Traversal Problem
Description
LeetCode Problem 429.
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:
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Input: root = [1,null,3,2,4,null,5,6]
Output: [[1],[3,2,4],[5,6]]
Example 2:
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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]
Sample C++ Code
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/*
// 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 {
public:
vector<vector<int>> levelOrder(Node* root) {
if (root == nullptr) return {};
queue<Node*> q;
q.push(root);
vector<vector<int>> ans;
while (!q.empty()) {
ans.emplace_back();
for (int i = q.size(); i >= 1; i--) {
Node* curr = q.front(); q.pop();
ans.back().push_back(curr->val);
for (Node* child : curr->children) {
q.push(child);
}
}
}
return ans;
}
};