gistfile1.cpp

#include <iostream>
#include <iomanip>
#include <fstream>
#include <vector>
#include <chrono>
#include <utility>
#include <cmath>

const size_t records_number = 1000000;
const size_t check_status_chunk_size = records_number / 100;
const size_t check_pass_chunk_size = records_number / 1000;

struct star_info
{
    long x,y,z;

    unsigned long long distance_square(const star_info& another_star_info) const
    {
        unsigned long long dx = x - another_star_info.x, dy = y - another_star_info.y, dz = z - another_star_info.z;

        return dx * dx + dy * dy + dz * dz;
    }
};

std::basic_istream<char>& operator>>(std::basic_istream<char>& is, star_info& str)
{
    is >> str.x >> str.y >> str.z;
    return is;
}

std::basic_ostream<char>& operator<<(std::basic_ostream<char>& is, const star_info& str)
{
    is << "{" << str.x << "; " << str.y << "; " << str.z << "}";
    return is;
}

template<class R, class T>
inline R duration(const T& time_point1,const T& time_point2)
{
    auto d = std::chrono::duration_cast<std::chrono::duration<R>>(time_point2 - time_point1);
    return d.count();
}

void print_loading_status(size_t percent)
{
    std::cout << "\rLoading: " << std::setw(3) << percent << " %";
}

template<class F>
void load_data(std::ifstream& data, std::vector<star_info>& stars, F process_data)
{
    auto t = std::chrono::high_resolution_clock::now();
    size_t i = 0;

    while (!data.eof() && i < records_number)
    {
        data >> stars[i];
        ++i;

        if (i % check_status_chunk_size == 0)
        {
            print_loading_status(i * 100.0 / records_number);
        }
    }
    std::cout << "\nDone! - " << duration<double>(t, std::chrono::high_resolution_clock::now()) << " sec" << std::endl << std::endl;

    process_data();
}

auto main() -> int
{
    auto t0 = std::chrono::high_resolution_clock::now();
    std::ifstream data("stars.dat");

    if (data.is_open())
    {
        std::vector<star_info> stars(records_number);

        load_data(data, stars, [&]()
        {
            unsigned long long min_distance_square = (unsigned long long)-1;
            size_t min_distance_square_star_indexes[2] = {0, 0};
            auto t1 = std::chrono::high_resolution_clock::now();
            auto t2 = t1;

            for (size_t current = 0; current < stars.size() - 1; ++current)
            {
                for (size_t i = current + 1; i < stars.size(); ++i)
                {
                    auto current_distance_square = stars[current].distance_square(stars[i]);

                    if (current_distance_square < min_distance_square)
                    {
                        min_distance_square = current_distance_square;
                        min_distance_square_star_indexes[0] = current;
                        min_distance_square_star_indexes[1] = i;
                    }
                }
                if ( current % check_pass_chunk_size == 0)
                {
                    std::cout << "Pass # " << current <<" done - " << duration<double>(t2, std::chrono::high_resolution_clock::now()) << " sec" << std::endl;
                    t2 = std::chrono::high_resolution_clock::now();
                }
            }

            std::cout << "\nAll passes done - " << duration<double>(t1, std::chrono::high_resolution_clock::now()) << " sec" << std::endl;
            std::cout << "Minimal distance = " << pow(min_distance_square, 0.5) << std::endl;
            std::cout << "Stars:{ID: " << min_distance_square_star_indexes[0] << ":" << stars[min_distance_square_star_indexes[0]] << "; ID: " << min_distance_square_star_indexes[1] << ":" << stars[min_distance_square_star_indexes[1]] << ")\n";
        });
    }
    else
    {
        std::cout << "Can't open data file!" << std::endl;
    }
    std::cout << "Work done - " << duration<double>(t0, std::chrono::high_resolution_clock::now()) << " sec" << std::endl;
    std::cin.get();
}