/*
VIM: let b:cf5build="clang -std=c++20 -O2 -pthread -lstdc++ -I. {SRC} -o {OUT}"
VIM: let b:cf5run="{OUT}"
*/
#include <iostream>
#include <exception>
#include <chrono>
#include <vector>

/*
Problem Description
    For given set of N elements print all possible subsets.

Sample inputs - Expected outputs
  {"a"} ->
       <- empty set
    a
  {"a", "b"} ->
       <- empty set
    a
    b
    a b
Input corner cases
    Empty input set yields to one empty subset.
*/

void printAllSubsets(const std::vector<std::string> &inputSet, std::ostream &os)
{
    std::vector<bool> subset(inputSet.size(), false);

    while (){

        std::cout << '[';
        for (size_t i = 0; i < inputSet.size(); ++i){
            if (subset[i]){
                std::cout << inputSet[i] << ' ';
            }
        }
        std::cout << ']' << std::endl;


        std::

    }
    std::vector<std::string>

}

int main ( void )
{try{
    auto begin = std::chrono::high_resolution_clock::now();


    //......
    const std::vector<std::string> inputSet = {"a", "b", "c", "d"};
    printAllSubsets(inputSet, std::cout);

    auto end = std::chrono::high_resolution_clock::now();
    std::chrono::duration<double> seconds = end - begin;
    std::cout << "Time: " << seconds.count() << std::endl;
    return 0;
}
catch ( const std::exception& e )
{
    std::cerr << std::endl
            << "std::exception(\"" << e.what() << "\")." << std::endl;
    return 2;
}
catch ( ... )
{
    std::cerr  << std::endl
            << "unknown exception." << std::endl;
    return 1;
}}