Clone N-ary Tree

给一个n个children的树, 求一个这个数的deep copy.

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

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

class Solution {
    public Node cloneTree(Node root) {
        if(root == null)
            return null; 
        Node cloned = new Node(root.val);
        for(int i = 0; i < root.children.size(); i++){
            cloned.children.add(cloneTree(root.children.get(i)));
        }
        return cloned;
    } 
}