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  1. using System;
  2. using System.Globalization;
  3. using System.Linq;
  4. using System.Collections.Generic;
  5.  
  6. public class Test
  7. {
  8. 	public static void Main()
  9. 	{
  10. 		var words = new List<string>{"golf", "hip", "hop", "hotel", "grass", "world", "wee"};
  11. 	    IEnumerable<string> lastWordOfConsecutiveFirstCharGroups = words
  12. 	        .GroupAdjacent(str => str[0])
  13. 	        .Select(g => g.Last());
  14. 	    Console.WriteLine(string.Join(",",lastWordOfConsecutiveFirstCharGroups.ToArray()));
  15.  
  16. 	    words=new List<string>{"apples", "armies", "black", "beer", "bastion", "cat", "cart", "able", "art", "bark"};
  17. 	    lastWordOfConsecutiveFirstCharGroups = words
  18. 	       .GroupAdjacent(str => str[0])
  19. 	       .Select(g => g.Last());
  20. 	    Console.WriteLine(string.Join(",",lastWordOfConsecutiveFirstCharGroups.ToArray()));
  21. 	}
  22. }
  23.  
  24. public static class Extensions
  25. {
  26.     public static IEnumerable<IGrouping<TKey, TSource>> GroupAdjacent<TSource, TKey>(
  27.         this IEnumerable<TSource> source,
  28.         Func<TSource, TKey> keySelector)
  29.     {
  30.         TKey last = default(TKey);
  31.         bool haveLast = false;
  32.         List<TSource> list = new List<TSource>();
  33.         foreach (TSource s in source)
  34.         {
  35.             TKey k = keySelector(s);
  36.             if (haveLast)
  37.             {
  38.                 if (!k.Equals(last))
  39.                 {
  40.                     yield return new GroupOfAdjacent<TSource, TKey>(list, last);
  41.                     list = new List<TSource>();
  42.                     list.Add(s);
  43.                     last = k;
  44.                 }
  45.                 else
  46.                 {
  47.                     list.Add(s);
  48.                     last = k;
  49.                 }
  50.             }
  51.             else
  52.             {
  53.                 list.Add(s);
  54.                 last = k;
  55.                 haveLast = true;
  56.             }
  57.         }
  58.         if (haveLast)
  59.             yield return new GroupOfAdjacent<TSource, TKey>(list, last);
  60.     }
  61.  
  62.     public class GroupOfAdjacent<TSource, TKey> : IEnumerable<TSource>, IGrouping<TKey, TSource>
  63.     {
  64.         public TKey Key { get; set; }
  65.         private List<TSource> GroupList { get; set; }
  66.         System.Collections.IEnumerator System.Collections.IEnumerable.GetEnumerator()
  67.         {
  68.             return ((System.Collections.Generic.IEnumerable<TSource>)this).GetEnumerator();
  69.         }
  70.         System.Collections.Generic.IEnumerator<TSource> System.Collections.Generic.IEnumerable<TSource>.GetEnumerator()
  71.         {
  72.             foreach (var s in GroupList)
  73.                 yield return s;
  74.         }
  75.         public GroupOfAdjacent(List<TSource> source, TKey key)
  76.         {
  77.             GroupList = source;
  78.             Key = key;
  79.         }
  80.     }
  81. }
Success #stdin #stdout 0.03s 33840KB
comments (?)
stdin
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Standard input is empty
stdout
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golf,hotel,grass,wee
armies,bastion,cart,art,bark
https://ideone.com/NVvMxw
language:
C# (gmcs 5.20.1)
created:
12 years ago
visibility:
public

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