MVC 多级目录菜单

{
    public class Class1
    {
        public int ID{get;set;}
        public int parentID { get; set; }
        public int childID { get; set; }
        public string title { get; set; }
    }

@using WebApplication1.Models;
    @{
        ViewBag.Title = "About";
    }
    <h2>@ViewBag.Title.</h2>
    <h3>@ViewBag.Message</h3>

    <p>Use this area to provide additional information.</p>

@{
    var totalList = new List<Class1>();//全部目录列表
    totalList.Add(new Class1{ ID = 1,parentID = 0, title = "title_1"});
    totalList.Add(new Class1{ ID = 5,parentID = 0, title = "title_5"});
    totalList.Add(new Class1{ ID = 12,parentID = 0, title = "title_12"});
    totalList.Add(new Class1{ ID = 2,parentID = 1, title = "title_2"});
    totalList.Add(new Class1{ ID = 3,parentID = 1, title = "title_3"});
    totalList.Add(new Class1{ ID = 4,parentID = 1, title = "title_4"});
    totalList.Add(new Class1{ ID = 6,parentID = 5, title = "title_6"});
    totalList.Add(new Class1{ ID = 7,parentID = 5, title = "title_7"});
    totalList.Add(new Class1{ ID = 8,parentID = 5, title = "title_8"});
    totalList.Add(new Class1{ ID = 9,parentID = 2, title = "title_9"});
    totalList.Add(new Class1{ ID = 10,parentID = 2, title = "title_10"});
    totalList.Add(new Class1{ ID = 11,parentID = 2, title = "title_11"});
    totalList.Add(new Class1{ ID = 13,parentID = 12, title = "title_13"});
    totalList.Add(new Class1{ ID = 14,parentID = 12, title = "title_14"});
    totalList.Add(new Class1{ ID = 15,parentID = 12, title = "title_15"});
    totalList.Add(new Class1{ ID = 16,parentID = 4, title = "title_16"});
    totalList.Add(new Class1{ ID = 17,parentID = 4, title = "title_17"});
    totalList.Add(new Class1{ ID = 18,parentID = 4, title = "title_18"});
    foreach (var item in totalList){
        <ul>
            @if (item.parentID == 0)
            {//如果为一级目录
                <li>@item.title</li>
                if (totalList.Find(x => x.parentID == item.ID ) != null)
                {
                    @Show(item);
                }
            }
        </ul>
    }
}

@helper Show(Class1 item){
    var totalList = new List<Class1>();//全部目录列表
    totalList.Add(new Class1 { ID = 1, parentID = 0, title = "title_1" });
    totalList.Add(new Class1 { ID = 5, parentID = 0, title = "title_5" });
    totalList.Add(new Class1 { ID = 12, parentID = 0, title = "title_12" });
    totalList.Add(new Class1 { ID = 2, parentID = 1, title = "title_2" });
    totalList.Add(new Class1 { ID = 3, parentID = 1, title = "title_3" });
    totalList.Add(new Class1 { ID = 4, parentID = 1, title = "title_4" });
    totalList.Add(new Class1 { ID = 6, parentID = 5, title = "title_6" });
    totalList.Add(new Class1 { ID = 7, parentID = 5, title = "title_7" });
    totalList.Add(new Class1 { ID = 8, parentID = 5, title = "title_8" });
    totalList.Add(new Class1 { ID = 9, parentID = 2, title = "title_9" });
    totalList.Add(new Class1 { ID = 10, parentID = 2, title = "title_10" });
    totalList.Add(new Class1 { ID = 11, parentID = 2, title = "title_11" });
    totalList.Add(new Class1 { ID = 13, parentID = 12, title = "title_13" });
    totalList.Add(new Class1 { ID = 14, parentID = 12, title = "title_14" });
    totalList.Add(new Class1 { ID = 15, parentID = 12, title = "title_15" });
    totalList.Add(new Class1 { ID = 16, parentID = 4, title = "title_16" });
    totalList.Add(new Class1 { ID = 17, parentID = 4, title = "title_17" });
    totalList.Add(new Class1 { ID = 18, parentID = 4, title = "title_18" });
    <ul>
        @for (int i = 0; i < totalList.Count; i++){
        if (item.ID == totalList[i].parentID){
            <li>@totalList[i].title</li>
            if (totalList.Find(x => x.parentID == totalList[i].ID) != null){
                @Show(totalList[i]);
            }
        }
        }
    </ul>
}