I’m sure something identical to this has been done, but I can’t find a direct answer.

A group of cards here is represented by a ulong with bits set. So, bit 0 is the 2 of clubs, bit 1 is the 3 of clubs, bit 13 is the 2 of diamonds…

A 2 card hand has 2 bits set, a 7 card hand has 7 bits set, obviously. So if you want to combine your hole cards with the board to see what you’ve got, you do

ulong myHoleCards = something;
ulong board = somethingElse;
ulong myHand = myHoleCards | board;

So DeaOutCards()is meant to deal out the board, or whatever, while taking into account that it shouldn’t deal cards that are already out. I believe it is dealing out certain hands too often, or too repetitively, which slightly fouls the results. I say “I believe” because it is tough to be certain where exactly the error is coming in. Am I making a mistake here, either in the logic or in my understanding of how random works?

using System.Diagnostics;
using System.Numerics;

namespace Enumerator;

public class Holdem
{
    private Random random { get; } = new();

    public ulong DealOutCards(int totalCards, ulong cardsAlreadyOut)
    {
        ulong returner = 0;

        // Keep dealing cards until brought up to the total
        // Cards already out will automatically be ignored by the or
        while (BitOperations.PopCount(returner | cardsAlreadyOut) < totalCards)
        {
            returner |= (1ul << random.Next(51));
        }

        // Remove any cards already out
        return returner & ~cardsAlreadyOut;
    }
}