返回最大深度

 Console.WriteLine(GetMaxDepth(list));
public static int GetMaxDepth(List<Department> list, int? id = null)
        {
            if (list == null) throw new Exception("未将对象引用设置到对象的实例。");
            var depaList = list.Where(x => x.FParentID == id).ToList();
            if (depaList.Count == 0) return 0;
            int max = 0;
            foreach (var item in depaList)
            {
                if (GetMaxDepth(list, item.FID) > max)
                {
                    max = GetMaxDepth(list, item.FID);
                }
            }
            return ++max;
            //Func<Guid, int> fun = null;
            //fun = new Func<Guid, int>(x =>
            //{
            //    return 1;
            //});
            //fun = delegate(Guid s)
            //{
            //};
        }