Get subsequence

#include <iostream>
#include <vector>
using namespace std;

void util(string s , int idx , string ans , vector<string> &res){
    
    if(idx == s.length()){
        res.push_back(ans);
        return;
    }
    
    char current = s[idx];
    util(s, idx+1 , ans , res);
    util(s,idx+1, ans + current , res);
    
 
    
}



int main() {
    string s = "abc";
    vector<string> res;
    
    util(s, 0, "",res);
    
    for(int i=0 ; i<res.size() ; i++){
        cout<<res[i]<<" ";
    }
    
    
}