Keno Simulator

#include <algorithm>
#include <functional>
#include <iostream>
#include <iterator>
#include <random>
#include <vector>



uint32_t constexpr NUM_BALLS = 80; // total balls in the game
uint32_t constexpr NUM_DRAWN = 20; // how many balls drawn for each game
uint32_t constexpr NUM_CHOSEN = 8; // how many balls player picks
uint32_t constexpr MILLION = 1e6;
uint32_t constexpr ROUNDS = 40 * MILLION;
uint32_t constexpr bet    = 4;

int64_t player_bankroll = 0;

int main(int argc, char *argv[])
{
    // create the RNG
    std::random_device rd;
    std::mt19937 rng(rd());

    // create and initialize the balls
    std::vector<int> balls(NUM_BALLS, 0);
    std::generate(balls.begin(), balls.end(), [n=1] () mutable { return n++; });

    // change the last number to 10000*bet for standard paytable, 60000 was to test
    // whether a progressive was positive-EV
    std::vector<int> awards{{ 0, 0, 0, 0, 2*bet, 13* bet, 100*bet, 1652*bet, 60000 }};

    for(uint32_t i=0; i < ROUNDS; ++ i)
    {
        std::shuffle(balls.begin(), balls.end(), rng);

        // out of the first 20 balls of the randomly shuffled set,
        // count how many are below "NUM_CHOSEN + 1", i.e. assuming the
        // player always picks numbers 1-n, since all combinations are equally likely,
        // it's easier to always choose 1-n for an n-spot game. +1 is so we include n
        player_bankroll += awards[ count_if(balls.begin(), balls.begin() + NUM_DRAWN,
            std::bind(std::less<int>(), std::placeholders::_1, NUM_CHOSEN + 1)) ];

        //std::copy(balls.begin(), balls.begin() + NUM_DRAWN, std::ostream_iterator<int>(std::cout, " "));
    }

    std::cout << "EV = " << static_cast<float>(ROUNDS * bet - player_bankroll)/static_cast<float>(player_bankroll);
    //player_bankroll -= ROUNDS * bet;
    //std::cout << "Bankroll = " << player_bankroll << std::endl;
    std::cout << "RTP = " << static_cast<float>(player_bankroll)/static_cast<float>(ROUNDS * bet);

    return 0;
}