c# - How to transform list of hierarchyid into a binary tree -

i working on multi-level marketing (binary) looks this:

(but binary tree not required perfect. node can have 0-2 child)

my problem data fetch database flat list.

notice using hierarchyid (sql server 2014)

basically textnode column breadcrumb.

every slash / represents level.

if have textnode of /1/ root. every node starts /1/ belongs root /1/, /1/1/ , /1/1/1/ (the root node included level 0)

i've tried accepted answer in question not working.

how can transform flatlist binary tree can traverse , display on screen?

im using c#, asp mvc 5, sql server 2014 if matters.

here simple implementation (assuming nodes in right order), may enhanced in multiple ways

public interface irow<out t> {     string textnode { get; }     t value { get; } }  public class treenode<t> {     private struct nodedescriptor     {         public int level { get; }         public int parentindex { get; }          public nodedescriptor(irow<t> row)         {             var split = row.textnode.split(new [] {"/"}, stringsplitoptions.removeemptyentries);             level = split.length;             parentindex = split.length > 1 ? int.parse(split[split.length - 2]) - 1 : 0;         }     }      public t value { get; }     public list<treenode<t>> descendants { get; }      private treenode(t value)     {         value = value;         descendants = new list<treenode<t>>();     }      public static treenode<t> parse(ireadonlylist<irow<t>> rows)     {         if (rows.count == 0)             return null;         var result = new treenode<t>(rows[0].value);         fillparents(new[] {result}, rows, 1, 1);         return result;     }      private static void fillparents(ilist<treenode<t>> parents, ireadonlylist<irow<t>> rows, int index, int currentlevel)     {         var result = new list<treenode<t>>();         (int = index; < rows.count; i++)         {             var descriptor = new nodedescriptor(rows[i]);             if (descriptor.level != currentlevel)             {                 fillparents(result, rows, i, descriptor.level);                 return;             }             var treenode = new treenode<t>(rows[i].value);             parents[descriptor.parentindex].descendants.add(treenode);             result.add(treenode);         }     } } 

sample usage:

public class row : irow<string> {     public string textnode { get; }     public string value { get; }      public row(string textnode, string username)     {         textnode = textnode;         value = username;     } }  class program {      static void main(string[] args)     {         irow<string>[] rows =         {             new row("/", "ahmed"),             new row("/1/", "saeed"),             new row("/2/", "amjid"),             new row("/1/1/", "noura"),             new row("/2/1/", "noura01"),             new row("/2/2/", "reem01"),             new row("/1/1/1", "under_noura")         };          var tree = treenode<string>.parse(rows);         printtree(tree);     }      private static void printtree<t>(treenode<t> tree, int level = 0)     {         string prefix = new string('-', level*2);         console.writeline("{0}{1}", prefix, tree.value);         foreach (var node in tree.descendants)         {             printtree(node, level + 1);         }     } }