using System;

using System.Linq;

using System.Collections.Generic;

​

​

[Flags]

public enum Colors

{

    None = 0,

    Yellow = 1,

    Blue = 2,

    Red = 4,

    White = 8,

}

​

public static class EnumHelper

{

    public static IEnumerable<T> GetFlagValues<T>(this Enum flags) where T: Enum

    {       

        return Enum.GetValues(typeof(T))

                         .Cast<T>()

                         .Where(x => flags.HasFlag(x));

    }

}

​

public class Program

{   

    private static void PrintMixedColorsInfo(string name, Colors color)

    {       

        IEnumerable<string> colors = color.GetFlagValues<Colors>().Except(new [] { Colors.None } ).Select(x => x.ToString());       

        if (colors.Count() == 1)

        {

            Console.WriteLine("Color \"" + name + "\" is not mixed. It's a primary color.");    

        }

        else

        {

            Console.WriteLine("Color \"" + name + "\" is mixed by: " + string.Join(" | ", colors)); 

        }

    }

    public static void Main()

    {

        var colors = new Dictionary<string, Colors>()

        {

            { "green", Colors.Yellow | Colors.Blue }, // 3

            { "orange", Colors.Yellow | Colors.Red }, // 5

            { "purple", Colors.Blue | Colors.Red }, // 6

            { "brown", Colors.Yellow | Colors.Blue | Colors.Red }, // 7,

            { "light green", Colors.Blue | Colors.Yellow | Colors.White }, // 11

            { "light orange", Colors.Yellow | Colors.Red | Colors.White }, // 13

            { "blue", Colors.Blue }, // 2

        };

        foreach(var color in colors)

        {

            PrintMixedColorsInfo(color.Key, color.Value);

        }

    }

}