Shuffle, C# - rextester

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//Rextester.Program.Main is the entry point for your code. Don't change it.
//Compiler version 4.0.30319.17929 for Microsoft (R) .NET Framework 4.5

using System;
using System.Collections.Generic;
using System.Linq;

namespace Rextester
{
    public class Program
    {
        public static void Main(string[] args)
        {

IEnumerable<Int32> source = Enumerable.Range(1, 20).Shuffle(Int32.MaxValue);
                    
          IEnumerable<Int32> expect = Enumerable.Range(1, 20).Shuffle(Int32.MaxValue);
                  
          foreach (Int32 n in source)
              Console.Write(n + " ");
            
          Console.WriteLine();
            
          foreach (Int32 n in expect)
              Console.Write(n + " ");
            
        }
        
    }
    
  public static class EnumerableExtensions {

public static IEnumerable<T> Shuffle<T>(this IEnumerable<T> source) {

return source.Shuffle(null);

} // Shuffle

public static IEnumerable<T> Shuffle<T>(this IEnumerable<T> source, Int32? seed) {

if (source == null) 
        throw new ArgumentNullException("source");

List<T> buffer = source.ToList();

Random random = seed.HasValue ? new Random(seed.Value) : new Random();

Int32 count = buffer.Count;

for (Int32 i = 0; i < count; i++) {          
        Int32 j = random.Next(i, count);
        yield return buffer[j];          
        buffer[j] = buffer[i];
      }

} // Shuffle

} // EnumerableExtensions    
    
}

Show compiler warnings [ + ] Show input
Compilation time: 0,16 sec, absolute running time: 0,08 sec, cpu time: 0,06 sec, average memory usage: 13 Mb, average nr of threads: 3