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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.     	public static IEnumerable<(T, int[])> Expand<T>(this IEnumerable<T> source, Func<T, IEnumerable<T>> getChildren) {
  44.     var stack = new Stack<IEnumerator<T>>();
  45.     var e = source.GetEnumerator();
  46.     List<int> indexes = new List<int>() { -1 };
  47.     try {
  48.         while (true) {
  49.             while (e.MoveNext()) {
  50.                 var item = e.Current;
  51.                 indexes[stack.Count]++;
  52.                 yield return (item, indexes.Take(stack.Count + 1).ToArray());
  53.                 var elements = getChildren(item);
  54.                 if (elements == null) continue;
  55.                 stack.Push(e);
  56.                 e = elements.GetEnumerator();
  57.                 if (indexes.Count == stack.Count)
  58.                     indexes.Add(-1);
  59.                 }
  60.             if (stack.Count == 0) break;
  61.             e.Dispose();
  62.             indexes[stack.Count] = -1;
  63.             e = stack.Pop();
  64.         }
  65.     } finally {
  66.         e.Dispose();
  67.         while (stack.Count != 0) stack.Pop().Dispose();
  68.     }
  69. }
  70.     }
  71.  
  72.     public class Node
  73.     {
  74.     	public int Id;
  75.     	public List<Node> Children;
  76.     }
  77.  
  78.     public class Test
  79.     {
  80.     	public static void Main()
  81.     	{
  82.     		List<Node> nodes = new List<Node>()
  83.     		{
  84.     			new Node()
  85.     			{
  86.     				Id = 1,
  87.     				Children = new List<Node>()
  88.     				{
  89.     					new Node()
  90.     					{
  91.     						Id = 2,
  92.     						Children = new List<Node>()
  93.     						{
  94.     							new Node()
  95.     							{
  96.     								Id = 4
  97.     							},
  98.     							new Node()
  99.     							{
  100.     								Id = 5
  101.     							}
  102.     						}
  103.     					},
  104.     					new Node()
  105.     					{
  106.     						Id = 3
  107.     					}
  108.     				}
  109.     			}
  110.     		};
  111.  
  112.     		Console.WriteLine(String.Join(", ", nodes.Traverse(n => n.Children).Select(n => n.Id)));
  113.     		Console.WriteLine(String.Join(", ", nodes.Expand(n => n.Children).Select(n => $"{n.Item1.Id}: { String.Join(", ", n.Item2)}")));
  114.     	}
  115.     }
Success #stdin #stdout 0.03s 29372KB
comments (?)
stdin
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Standard input is empty
stdout
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1, 2, 4, 5, 3
1: 0, 2: 0, 0, 4: 0, 0, 0, 5: 0, 0, 1, 3: 0, 1
https://ideone.com/FUv2ab
language:
C# (gmcs 5.20.1)
created:
6 days ago
visibility:
public

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