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

    public Node() {}

    public Node(int _val) {
        val = _val;
    }

    public Node(int _val, List<Node> _children) {
        val = _val;
        children = _children;
    }
};
*/

class Solution {
    public List<List<Integer>> levelOrder(Node root) {
        if(root == null) return List.of();
        List<List<Integer>> ans = new ArrayList<>();
        Queue<Node> q = new ArrayDeque<>();
        q.add(root);

        while(!q.isEmpty()){
            int n = q.size();
            List<Integer> vals = new ArrayList<>(n);
            while(n -- > 0){
                Node node = q.poll();
                vals.add(node.val);
                q.addAll(node.children);
            }

            ans.add(vals);
        }

        return ans;
    }
}