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  1.     using System;
  2.     using System.Linq;
  3.     using System.Collections.Generic;
  4.  
  5.     public static class MyExtensions
  6.     {
  7.     	public static IEnumerable<T> Traverse<T>(
  8.     	    this IEnumerable<T> source,
  9.     	    Func<T, IEnumerable<T>> fnRecurse)
  10.     	{
  11.     		if (source != null)
  12.     		{
  13.     			Stack<IEnumerator<T>> enumerators = new Stack<IEnumerator<T>>();
  14.     			try
  15.     			{
  16.     				enumerators.Push(source.GetEnumerator());
  17.     				while (enumerators.Count > 0)
  18.     				{
  19.     					var top = enumerators.Peek();
  20.     					while (top.MoveNext())
  21.     					{
  22.     						yield return top.Current;
  23.  
  24.     						var children = fnRecurse(top.Current);
  25.     						if (children != null)
  26.     						{
  27.     							top = children.GetEnumerator();
  28.     							enumerators.Push(top);
  29.     						}
  30.     					}
  31.  
  32.     					enumerators.Pop().Dispose();
  33.     				}
  34.     			}
  35.     			finally
  36.     			{
  37.     				while (enumerators.Count > 0)
  38.     					enumerators.Pop().Dispose();
  39.     			}
  40.     		}
  41.     	}
  42.     }
  43.  
  44.     public class Node
  45.     {
  46.     	public int Id;
  47.     	public List<Node> Children;
  48.     }
  49.  
  50.     public class Test
  51.     {
  52.     	public static void Main()
  53.     	{
  54.     		List<Node> nodes = new List<Node>()
  55.     		{
  56.     			new Node()
  57.     			{
  58.     				Id = 1,
  59.     				Children = new List<Node>()
  60.     				{
  61.     					new Node()
  62.     					{
  63.     						Id = 2,
  64.     						Children = new List<Node>()
  65.     						{
  66.     							new Node()
  67.     							{
  68.     								Id = 4
  69.     							},
  70.     							new Node()
  71.     							{
  72.     								Id = 5
  73.     							}
  74.     						}
  75.     					},
  76.     					new Node()
  77.     					{
  78.     						Id = 3
  79.     					}
  80.     				}
  81.     			}
  82.     		};
  83.  
  84.     		Console.WriteLine(String.Join(", ", nodes.Traverse(n => n.Children).Select(n => n.Id)));
  85.     	}
  86.     }
Success #stdin #stdout 0.02s 18512KB
comments (?)
stdin 
Standard input is empty
stdout 
1, 2, 4, 5, 3
https://ideone.com/y7Uf0p
language:
C# (gmcs 5.20.1)
created:
3 years ago
visibility:
public

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