Finding all combinations from sets of possibilities

Question

I have multiple sets of arrays that contain additional arrays that have values attached that I use for figuring out math. In order to find the best combination of these things,

Answer 1

Assuming you are using a version of C# which supports LINQ:

static void Main(string[] args)
    {
        // declare some lists
        var aList = new string[] { "a1", "a2", "a3" };
        var bList = new string[] { "b1", "b2", "b3" };
        var cList = new string[] { "c1", "c2", "c3" };

        // do the equivalent of a SQL CROSS JOIN
        var permutations = aList
            .Join(bList, a => "", b => "", (a, b) => new string[] { a, b })
            .Join(cList, ab => "", c => "", (ab, c) => new string[] { ab[0], ab[1], c });

        // print the results
        Console.WriteLine("Permutations:");
        foreach (var p in permutations)
            Console.WriteLine(string.Join(", ", p));
    }

The Join calls with the lambda expressions pointing the strings to empty strings causes the Join function to treat the strings as equal, emulating a SQL CROSS JOIN.