Fórum ➡ What values have the greatest frequency? ♦, C#

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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;
using System.Text.RegularExpressions;

// aljodav ➡ rextester.com/users/376

// in reply to MSDN thread: bit.ly/2iGdFNn

namespace Rextester
{
    public class Program
    {
        public static void Main(string[] args)
        {
            // what values have the greatest frequency in this array?
            int[] arr={
                11,12,123,-1,123,9,5,7,9,3,
                -1,8,123,7,9,5,-1,2,3,7,
                1,9,-1,7,9,7,123,123,-1,-6,
                -99,-99,-99,-99,55,44,78,-99,-60,-60,
            };
            
            arr
                .GroupBy(e=>e,(e,es)=>new/*y*/{Value=e,Frequency=es.Count()})
                .GroupBy(y=>y.Frequency,(f,ys)=>new/*x*/{Frequency=f,Values=ys.ToList()})
                .OrderByDescending(x=>x.Frequency)
                .First()/*first x from ordered xs*/
                .Values/*property from first x*/
                .ForEach/*value from List<y>*/(Console.WriteLine)
                ;
            
            Console.WriteLine("\n\nHello, world!");
        }
    }
}

Show compiler warnings [ + ] Show input
Compilation time: 0,16 sec, absolute running time: 0,11 sec, cpu time: 0,12 sec, average memory usage: 15 Mb, average nr of threads: 3