#include <iostream>

#include <vector>

using namespace std ;

void printF(int index , vector<int> &ds , int arr[] , int n)

{

if(index == n)

{

// print the vector

for(auto it : ds)

{

cout<< it << " " ;

}

if(ds.size() == 0)

{

cout<< "{}" ;

}

cout<<endl;

return ;

}

// take or pick the particular index into the subsequence

ds.push_back(arr[index]);

printF(index + 1 , ds , arr , n);

ds.pop_back();

// not pick, or not take condition, this elemnt is not added to your subsequence

printF(index + 1 , ds , arr , n);

}

int main() {

int arr[] = {3 , 1 , 2} ;

int n = 3 ; // size of array ;

vector<int> ds ; // to carry all subsequence

printF(0 , ds , arr , n);

return 0;

}

//tc 2^n

//sc n

//https://www.youtube.com/watch?v=AxNNVECce8c&list=PLgUwDviBIf0rGlzIn_7rsaR2FQ5e6ZOL9&index=6