#include <iostream>
using namespace std;
int n = 3;
void f(int i, bool choice[]){
if(i==n+1){
for(int j = 1; j <= n;j++){
if(choice[j])
cout << j << " ";
}
cout << endl;
return ;
}
choice[i] = false;
f(i+1,choice);
choice[i] = true;
f(i+1,choice);
}
int main() {
// your code goes here
bool v[20];
f(1,v);
return 0;
}
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