using System;

using System.Linq;

public class Program

{

    public static void Main()

    {

        int[] array1 = { 2, 5, 8, 10, 2, 23, 2, 4, 5, 8, 8 };

​

        int[] arraySemRepeticao = array1.Distinct().ToArray();

        var arrayAgrupadosRepeticao = array1.GroupBy(x => x)

            .Select(a => new

                    {

                        Item = a.Key,

                        Quant = a.Count()

                    })

            .ToArray();

        foreach(var a in arraySemRepeticao.OrderBy(x => x))

        {

            Console.WriteLine(a);

        }

        Console.WriteLine();

        Console.WriteLine("---------------------------------------------");

        Console.WriteLine();

        foreach(var a in arrayAgrupadosRepeticao)

        {

            Console.WriteLine(a.Item + " " + a.Quant);

        }

    }

}