fizzbuzz.cpp

#include <algorithm>
#include <cstdint>
#include <iostream>
#include <mutex>
#include <random>
#include <thread>

using namespace std;
using u32 = uint_fast32_t;
using nl = numeric_limits<u32>;

mutex m;

auto find_seed(u32 max, u32 delta) {
    return [=]{
        thread_local mt19937 gen;
        thread_local uniform_int_distribution<u32> dist{0, 3};
        thread_local const vector<u32> v{{0, 0, 1, 0, 2, 1, 0, 0, 1, 2, 0, 1, 0, 0, 3}};
        for (auto i = max - delta; i < max; ++i) {
            gen.seed(i);
            if (all_of(begin(v), end(v), [&](auto x){ return x == dist(gen); })) {
                unique_lock<mutex> l{m};
                cout << i << '\n';
            }
        }
    };
}

int main() {
    vector<thread> v;
    for (auto i = thread::hardware_concurrency(), d = nl::max() / i; i > 0; --i) {
         v.emplace_back(find_seed(i * d, d));
    }

    for (auto& t : v) {
        t.join();
    }
}