Maximum Depth of N-ary Tree

给一个n叉树, 返回最深的depth.

class Solution {
    public int maxDepth(Node root) {
        if(root == null)
            return 0;
        int res = 0;
        for(Node n : root.children) {
            res = Math.max(res, maxDepth(n));
        }
        return res+1;
    }
}