问个递归算法解决方案

问个递归算法
id pid remark
1 0 A

2 0 A

3 1 B
 
4 1 B

5 3 C 

6 3 C

7 4 D 
 
8 2 D

如果有个LIST存放了8行上面的数据，第一列是父信息，第二列是子信息，0则是顶层，remark是额外判断条件，

比如 1 0 下面所有子信息有 3 1，4 1，5 3，6 3，7 4；1 0下面所有remark为C的则有 5 3，6 3，我想问的是如何通过递归算法得出1 0 的子信息？最好是用linq to object



[解决办法]

C# code

public class recursionList    {        public recursionList(int id,int pid,string remark)        {            this.id = id;            this.pid = pid;            this.remark = remark;        }        public int id { get; set; }        public int pid { get; set; }        public string remark { get; set; }    } public static List<recursionList> GetAllChirlds(List<recursionList> source,int id)        {           List<recursionList> result = new List<recursionList>();           recursionList parentM=source.FirstOrDefault(e => e.id == id);           List<recursionList> chirldMs = source.Where(e => e.pid == parentM.id).ToList();           if (chirldMs.Count > 0)           {               result.AddRange(chirldMs);               foreach (var item in chirldMs)               {                   List<recursionList> subsubs = GetAllChirlds(source, item.id);                   if (subsubs.Count > 0)                       result.AddRange(subsubs);               }           }           return result;        }public static void Main(string[] args)        {            List<recursionList> templist = new List<recursionList>() {             new recursionList(1,0,"A"),            new recursionList(2,0,"A"),            new recursionList(3,1,"B"),            new recursionList(4,1,"B"),            new recursionList(5,3,"C"),            new recursionList(6,3,"C"),            new recursionList(7,4,"D"),            new recursionList(8,2,"D"),            };            var allsubs = GetAllChirlds(templist, 1);      }