#include <iostream>
#include <chrono>
#include <functional>
#include <vector>
#include <random>

namespace {
constexpr size_t sz = 1e8;
constexpr long long MOD = 1e9;
} // namespace

template <class Foo, class... Args> std::time_t get_duration(Foo func, Args&... args) {
    auto start = std::chrono::high_resolution_clock::now();
    func(args...);
    auto stop = std::chrono::high_resolution_clock::now();
    return std::chrono::duration_cast<std::chrono::milliseconds>(stop - start).count();
}

void with_RBF(std::vector<long long> const& vec) {
    long long sum = 0;
    for (const long long& elem : vec) {
        sum = (sum + elem) % MOD;
    }
}

void with_operator(std::vector<long long> const& vec) {
    long long sum = 0;
    for (size_t i = 0; i < sz; ++i) {
        sum = (sum + vec[i]) % MOD;
    }
}


void with_at(std::vector<long long> const& vec) {
    long long sum = 0;
    for (size_t i = 0; i < sz; ++i) {
        sum = (sum + vec.at(i)) % MOD;
    }
}


int main() {
    std::vector<long long> vec(sz);
    std::random_device rd;
    std::mt19937 gen(rd());
    std::uniform_int_distribution<long long> uidis(0);

    for (long long& elem : vec) elem = uidis(gen);

    std::time_t rbf_time = get_duration(with_RBF, vec);
    std::time_t operator_time = get_duration(with_operator, vec);
    std::time_t at_time = get_duration(with_at, vec);


    // AMD A6-6310 4 cores 1800 MHz, 4 gb DDR3

    std::cout << "rbf_time == " << rbf_time << " ms\n"; // 2748 ms
    std::cout << "operator_time == " << operator_time << " ms\n"; // 1900 ms
    std::cout << "at_time == " << at_time << " ms\n"; // 2842 ms

    return 0;
}