Generate and shuffle a list of cards with 3 copies of each value 1 through 8.

public static List<int> GenerateAndShuffleDeck()
{
    List<int> deck = new List<int>();
    for (int i = 0; i < 8; i++)
    {
        deck.Add(i + 1);
        deck.Add(i + 1);
        deck.Add(i + 1);
    }
    Random random = new Random();
    List<int> result = new List<int>();
    while (deck.Count > 0)
    {
        int index = random.Next(deck.Count);
        result.Add(deck[index]);
        deck.RemoveAt(index);
    }
    return result;
}