//-----------------------------------------------------------------------------
// struct-etal.cc
//-----------------------------------------------------------------------------

#include <chrono>
#include <functional>
#include <iomanip>
#include <iostream>
#include <numeric>
#include <random>
#include <typeinfo>

//-----------------------------------------------------------------------------

const int N = 2048, REP = 2048;

//-----------------------------------------------------------------------------

std::random_device device;
std::default_random_engine generator(device());
std::uniform_int_distribution<int> distribution(0, 9);
auto rng = std::bind(distribution, generator);

//-----------------------------------------------------------------------------

struct S
{
    int a, b;
    S() : a(rng()), b(rng()) {}
} const s[N];

int R[REP + 1]; // because... for (int ii = 1; ii <= REP; ++ii)

//-----------------------------------------------------------------------------

void v0()
{
    for (int ii = 1; ii <= REP; ++ii)
    {
        int X1 = 0, X2 = 0;

        for (int i = 0; i < N; ++i)
            X1 += 2 * s[i].a + ii;

        for (int i = 0; i < N; ++i)
            X2 += 3 * s[i].b - ii;

        if (X1 < X2)
            R[ii] = X1;
        else
            R[ii] = X2;
    }
}

//-----------------------------------------------------------------------------

void v1()
{
    for (int ii = 1; ii <= REP; ++ii)
    {
        int X1 = 0, X2 = 0;

        for (int i = 0; i < N; ++i)
        {
            X1 += 2 * s[i].a + ii;
            X2 += 3 * s[i].b - ii;
        }

        if (X1 < X2)
            R[ii] = X1;
        else
            R[ii] = X2;
    }
}

//-----------------------------------------------------------------------------

void v2()
{
    for (int ii = 1; ii <= REP; ++ii)
    {
        int X1 = 0, X2 = 0;

        for (int i = 0; i < N; i += 2)
        {
            X1 += 2 * (s[i].a + s[i + 1].a) + 2 * ii;
            X2 += 3 * (s[i].b + s[i + 1].b) - 2 * ii;
        }

        if (X1 < X2)
            R[ii] = X1;
        else
            R[ii] = X2;
    }
}

//-----------------------------------------------------------------------------

void v3()
{
    for (int ii = 1; ii <= REP; ++ii)
    {
        int X1 = 0, X2 = 0;

        for (int i = 0; i < N; ++i)
        {
            X1 += s[i].a;
            X2 += s[i].b;
        }

        X1 = 2 * X1 + N * ii;
        X2 = 3 * X2 - N * ii;

        if (X1 < X2)
            R[ii] = X1;
        else
            R[ii] = X2;
    }
}

//-----------------------------------------------------------------------------

void v4()
{
    int aa = 0, bb = 0;

    for (int i = 0; i < N; ++i)
    {
        aa += s[i].a;
        bb += s[i].b;
    }

    for (int ii = 1; ii <= REP; ++ii)
    {
        int X1 = 2 * aa + N * ii, X2 = 3 * bb - N * ii;

        if (X1 < X2)
            R[ii] = X1;
        else
            R[ii] = X2;
    }
}

//-----------------------------------------------------------------------------

void v5()
{
    int aa = 0, bb = 0;

    for (int i = 0; i < N; ++i)
    {
        aa += s[i].a;
        bb += s[i].b;
    }

    for (int ii = 1; ii <= REP; ++ii)
        R[ii] = std::min(2 * aa + N * ii, 3 * bb - N * ii);
}

//-----------------------------------------------------------------------------

template<class F> void test(F &f, const char *name)
{
    const unsigned TEST = 33;
    std::chrono::duration<double, std::micro> m[TEST];

    for (auto &i : m)
    {
        std::fill(R, R + REP, 0);

        auto start = std::chrono::high_resolution_clock::now();
        f();
        auto stop = std::chrono::high_resolution_clock::now();
        i = stop - start;
    }

    std::nth_element(m, m + TEST / 2, m + TEST);
    std::cout << "function: " << name << "\t time: " << std::fixed
              << std::setprecision(2) << std::setw(10) << m[TEST / 2].count()
              << " us\t result = " << std::accumulate(R + 1, R + REP + 1, 0)
              << std::endl;
}

//-----------------------------------------------------------------------------

int main()
{
    test(v0, "v0");
    test(v1, "v1");
    test(v2, "v2");
    test(v3, "v3");
    test(v4, "v4");
    test(v5, "v5");
}

//-----------------------------------------------------------------------------