429. N-ary Tree Level Order Traversal**
https://leetcode.com/problems/n-ary-tree-level-order-traversal/
题目描述
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]
C++ 实现 1
层序遍历使用队列来实现.
/*
// 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) return {};
queue<Node*> q;
q.push(root);
vector<vector<int>> res;
while (!q.empty()) {
auto size = q.size();
vector<int> tmp;
while (size --) {
auto r = q.front();
q.pop();
tmp.push_back(r->val);
for (auto &c : r->children)
q.push(c);
}
res.push_back(tmp);
}
return res;
}
};