using System;

using System.Linq;

​

static class Program

{

    public static void Main()

    {

        var none = Array.Empty<string>();

​

        string[][][] sets = 

        {

            new[] {none, new[] {"Product1"},             new[] {"Product1", "Product1"}},

            new[] {none, new[] {"Product2", "Product2"}, new[] {"Product2", "Product2", "Product2"}},

            new[] {none, new[] {"Product3"},             new[] {"Product3", "Product3"}},

        };

​

        Combine(sets, print);

    }

​

    static void print(string[][] strings)

    {

        bool emptySet = true; // Exactly one combination of products will contain zero of each; this will detect it.

​

        foreach (var set in strings.Where(set => set.Length > 0))

        {

            emptySet = false;

            Console.Write(string.Join(", ", set) + "; ");

        }

​

        if (!emptySet) // No need to write a new line if there were zero of each product.

            Console.WriteLine();

    }

​

    public static void Combine<T>(T[][] sets, Action<T[]> output)

    {

        combine(sets, 0, new T[sets.Length], output);

    }

​

    static void combine<T>(T[][] sets, int set, T[] combination, Action<T[]> output)

    {

        for (int i = 0; i < sets[set].Length; ++i)

        {

            combination[set] = sets[set][i];

​

            if (set < (sets.Length - 1))

                combine(sets, set + 1, combination, output);

            else 

                output(combination);

        }

    }

}

​