Fórum ➡ Get all combinations for ▶different◀ Id's ( GroupBy version ) ♦, 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
// http://rextester.com/users/376

// in reply to the thread
// https://social.msdn.microsoft.com/Forums/WindowsServer/en-us/b12e4766-cd22-455d-9474-46c4b865dd45/help-needed-to-get-combinations-in-a-list-of-objects?forum=csharpgeneral
// which is similar to
// http://stackoverflow.com/questions/10519619/create-all-possible-combinations-of-items-in-a-list-using-linq-and-c-sharp

// NOTICE that the quantity of ▶different◀ Id's is, theoretically, UNLIMITED.

namespace Rextester
{
    using LS=List<string>;
    using T2=Tuple<int,string>;
    using LT2=List<Tuple<int,string>>;
    class Program
    {
        static LT2 TheList(){
            return new LT2{
                new T2(3,"cotton"),
                new T2(3,"silk"),
                new T2(1,"red"),
                new T2(1,"blue"),
                new T2(2,"medium"),
                new T2(2,"small"),
                new T2(2,"large"),
                new T2(1,"green"),
            };
        }
        //  -----------------------------------------------------------------------
        
        public static void Main(string[] args)
        {
            /*1▶*/LS target=new LS();
            
            /*2▶*/TheList().GroupBy(x=>x.Item1).OrderBy(x=>x.Key).ToList().ForEach(x=>{
                if(0==target.Count){
                    target=x.Select(y=>y.Item2).ToList();
                }else{
                    LS tmp=target;target=new LS();
                    tmp.ForEach(y=>{
                        x.Select(z=>z.Item2).ToList().ForEach(z=>target.Add(y+","+z));
                    });
                }
            });
            
            /*3▶*/target.ForEach(Console.WriteLine);
            
            Console.WriteLine("\n\nHello, world!");
        }
    }
}

Show compiler warnings [ + ] Show input
Compilation time: 0,23 sec, absolute running time: 0,14 sec, cpu time: 0,14 sec, average memory usage: 15 Mb, average nr of threads: 3

Fórum ➡ Get all combinations for ▶different◀ Id's ( GroupBy version ) ...