Creating a random name generator. How do I accomplish this?

I'm trying to grab a single item from each of the Lists here, and combine them to make a unique name. This is just for kicks. :)

Here are the lists:

List<string> FirstNames = new List<string>()
{
    "Sergio",
    "Daniel",
    "Carolina",
    "David",
    "Reina",
    "Saul",
    "Bernard",
    "Danny",
    "Dimas",
    "Yuri",
    "Ivan",
    "Laura"
};

List<string> LastNamesA = new List<string>()
{
    "Tapia",
    "Gutierrez",
    "Rueda",
    "Galviz",
    "Yuli",
    "Rivera",
    "Mamami",
    "Saucedo",
    "Dominguez",
    "Escobar",
    "Martin",
    "Crespo"
};

List<string> LastNamesB = new List<string>()
{
    "Johnson",
    "Williams",
    "Jones",
    "Brown",
    "David",
    "Miller",
    "Wilson",
    "Anderson",
    "Thomas",
    "Jackson",
    "White",
    "Robinson"
};

I know I get a single item via an index, and I also know that I can use the Random class to generate a random number from 0 to ListFoo.Count.

What I don't know is how to check if a random permutation has already been drawn from the collections.

I've thought about using the tuple class:

List<Tuple<int,int,int>> permutations = new List<Tuple<int,int,int>>();

But I'm having a brainfart here. ;) Any guidance? I'm not really looking for the entire code to this simple problem, just a suggestion or hint.

EDIT

Thanks to the suggestions given here, here what I've come up with. Any room for improvements?

static void Main(string[] args)
{
    List<string> FirstNames = new List<string>()
    {
        "Sergio",
        "Daniel",
        "Carolina",
        "David",
        "Reina",
        "Saul",
        "Bernard",
        "Danny",
        "Dimas",
        "Yuri",
        "Ivan",
        "Laura"
开发者_StackOverflow    };

    List<string> LastNamesA = new List<string>()
    {
        "Tapia",
        "Gutierrez",
        "Rueda",
        "Galviz",
        "Yuli",
        "Rivera",
        "Mamami",
        "Saucedo",
        "Dominguez",
        "Escobar",
        "Martin",
        "Crespo"
    };

    List<string> LastNamesB = new List<string>()
    {
        "Johnson",
        "Williams",
        "Jones",
        "Brown",
        "David",
        "Miller",
        "Wilson",
        "Anderson",
        "Thomas",
        "Jackson",
        "White",
        "Robinson"
    };

    var permutations = new List<Tuple<int, int, int>>();
    List<string> generatedNames = new List<string>();

    Random random = new Random();
    int a, b, c;

    //We want to generate 500 names.
    while (permutations.Count < 500)
    {
        a = random.Next(0, FirstNames.Count);
        b = random.Next(0, FirstNames.Count);
        c = random.Next(0, FirstNames.Count);

        Tuple<int, int, int> tuple = new Tuple<int, int, int>(a, b, c);

        if (!permutations.Contains(tuple))
        {
            permutations.Add(tuple);
        }
    }

    foreach (var tuple in permutations)
    {
        generatedNames.Add(string.Format("{0} {1} {2}", FirstNames[tuple.Item1], 
                                                        LastNamesA[tuple.Item2],
                                                        LastNamesB[tuple.Item3])
        );
    }

    foreach (var n in generatedNames)
    {
        Console.WriteLine(n);
    }

    Console.ReadKey();
}

You are on the right track! Every time you generate a name, add it to your tuple list

//Create the tuple
Tuple <int, int, int> tuple = new Tuple<int, int, int>(index1, index2, index3)

if(!permutations.Contains(tuple))
{ 
    permutations.Add(tuple);
    //Do something else
}

I would think the simplest solution is to just the stuff the assembled name into a HashSet<string> which will ensure the list of created names is unique.

An alternative to the HashSet answer is to build all of the possible combinations in advance, shuffle them, then store them in a Queue, where you can retrieve them one at a time. This will avoid having to check the existing ones every time you build a new one, and will still be random.

This only works if you don't have a large set to begin with, since the work involved in creating the complete list and shuffling it would be huge for a large set of data.

It's really easy to generate them all using LINQ:

var combs =
(from first in FirstNames
from second in LastNamesA
from third in LastNamesB
select new Tuple<string, string, string>(first, second, third)).ToList();

After this, if you need to take unique elements from the list randomly, just shuffle the list and then pick them one-by-one in order.

You can use the Knuth-Fisher-Yates algorithm (that's an in-place shuffle):

Random rand = new Random();

for (int i = combs.Count - 1; i > 0; i--)
{
    int n = rand.Next(i + 1);
    var mem = combs[i];
    combs[i] = combs[n];
    combs[n] = mem;
}

I would create a HashSet<int> and store the numeric representation of the picks (eg 135 for first, third and 5th or use 010305) and then check if they are in the set.

1. Create a new tuple with 3 random digits
2. Check if permutations contains your new tuple
3. If not => Add new tuple to the list. If yes, start with point 1 again.