combo.cpp

como.cpp

#include <iostream>

using namespace std;

void combos(string soFar, string rest, string full){
  if(rest == ""){
    int len = full.length();
    for(int i = 0, j = 0; i < len; i++)
    {
      if(i == (int)(soFar[j] - '0')){
        cout << (char)(full[i] - 32) << " ";
        j++;
      }
      else
        cout << full[i] << " ";
    }
    cout << endl;
  }
  else {
    string current = rest.substr(0,1);
    string remaining = rest.substr(1);
    combos(soFar + current, remaining,full);
    combos(soFar,remaining,full);
  }
}

void print_combos(string s){
  int len = s.length();
  string str(len,' ');
  for(int i = 0; i < len; i++)
    str[i] = char(i+48);
  combos("",str,s);
}

int main(){
  print_combos("hello");
}