сияй

#include <iostream>
#include <fstream>
#include <ctime>

constexpr std::size_t MAX_INPUT_INTEGER = INT_MAX;

struct BitsContainer
{
    unsigned int *arr;
    std::size_t length;
};

BitsContainer createContainer()
{
    BitsContainer buffer;

    buffer.arr = new unsigned int[MAX_INPUT_INTEGER / 32 + 1]();
    buffer.length = MAX_INPUT_INTEGER / 32 + 1;

    return buffer;
}

void printContainer(BitsContainer& bctrDist)
{
    for (size_t i = 0; i < bctrDist.length; i++)
    {
        for (size_t j = 0; j < 32; j++)
        {
            if (bctrDist.arr[i] & (1 << j)) std::cout << "1";
            else std::cout << "0";
        }
    }
}

void setBit(BitsContainer& bctrDist, std::size_t n)
{
    std::size_t t = n / 32;
    int tnn = n % 32;

    bctrDist.arr[t] |= (1 << tnn);
}

void readFile(std::string path, BitsContainer& bctrDist)
{
    std::ifstream file;
    file.open(path);

    if (!file.is_open()) { std::cout << "FILE NOT FOUND" << std::endl; }

    while (!file.eof())
    {
        unsigned int buffer;
        file >> buffer;

        setBit(bctrDist, buffer);
    }
}

void writeFile(std::string path, BitsContainer& bctrDist)
{
    std::ofstream file;
    file.open(path);

    if (!file.is_open()) { std::cout << "FILE NOT CREATED!" << std::endl; }

    for (size_t i = 0; i < bctrDist.length; i++)
    {
        for (size_t j = 0; j < 32; j++)
        {
            if (bctrDist.arr[i] & (1 << j)) { file << 32 * i + j << " "; }
        }
    }
}

int main(int argc, char **argv)
{
    std::clock_t t0 = clock();

    auto t = createContainer();
    readFile("file.txt", t);
    //printContainer(t);
    writeFile("sorted.txt", t);

    t0 = clock() - t0;

    std::cout << t0 << " ms";
}