用迭代實現無限級分類

說起那個無限級分類，相信很多人都知道是什么東西，也曾經做過。我也相信，大家用得最多的實現方式就是做一個遞歸。

最近我也要做一個帶無限級分類的菜單，但是我又不想用遞歸來做，所以我需要用其他方式來實現，那就是迭代了。

首先，我需要定義一個實體模型，這舉一個省市無限級的例子：

    class Loaction    {        public int ID { get; set; }        public int PID { get; set; }        public string Name { get; set; }    //地方名        public int Level { get; set; }      //深度    }

然后寫方法，這里需要利用到棧的后進先出的特點：

        public static List<Loaction> Soft(List<Loaction> data, int pid)        {            Stack task = new Stack();            task.Push(pid);            List<Loaction> tree = new List<Loaction>();            int level = 0;            while (task.Count > 0)            {                bool flag = false;                for (int i = 0; i < data.Count; i++)                {                    var l = data[i];                    if (l.PID == pid)                    {                        pid = l.ID;                        task.Push(l.ID);                        l.Level = level;                        level++;                        tree.Add(l);                        data.Remove(l);                        i--;                        flag=true;                    }                }                if (!flag)                {                    task.Pop();                    if (task.Count > 0)                    {                        pid = Convert.ToInt32(task.Peek());                        level--;                    }                }            }            return tree;        }

最后準備數據->調用->輸出：

        static void Main(string[] args)        {            var data = new List<Loaction>();            data.Add(new Loaction() { ID = 1, PID = 0, Name = "北京" });            data.Add(new Loaction() { ID = 2, PID = 0, Name = "廣東" });            data.Add(new Loaction() { ID = 3, PID = 0, Name = "上海" });            data.Add(new Loaction() { ID = 4, PID = 0, Name = "重慶" });            data.Add(new Loaction() { ID = 5, PID = 0, Name = "黑龍江" });            data.Add(new Loaction() { ID = 6, PID = 1, Name = "豐臺" });            data.Add(new Loaction() { ID = 7, PID = 1, Name = "海淀" });            data.Add(new Loaction() { ID = 8, PID = 1, Name = "石景山" });            data.Add(new Loaction() { ID = 9, PID = 3, Name = "上海市" });            data.Add(new Loaction() { ID = 10, PID = 2, Name = "廣州" });            data.Add(new Loaction() { ID = 11, PID = 5, Name = "齊齊哈爾" });            data.Add(new Loaction() { ID = 12, PID = 2, Name = "茂名" });            data.Add(new Loaction() { ID = 13, PID = 2, Name = "深圳" });            data.Add(new Loaction() { ID = 14, PID = 5, Name = "哈爾濱" });            data.Add(new Loaction() { ID = 15, PID = 4, Name = "重慶市" });            data.Add(new Loaction() { ID = 16, PID = 2, Name = "東莞" });            data.Add(new Loaction() { ID = 17, PID = 2, Name = "中山" });            data.Add(new Loaction() { ID = 18, PID = 16, Name = "厚街鎮" });            var tree = Soft(data, 0);            foreach (var t in tree)            {                var sb = new StringBuilder();                for (int i = 0; i < t.Level; i++)                {                    sb.Append("  ");                                   }                 sb.Append(t.Name);                Console.WriteLine(sb.ToString());            }            Console.ReadKey();        }

然后效果如下：

就是這個樣子。。。。。(END)