Subset generation using Recursion

// I can't tell you what it really is,
// I can only tell you what it feels like.
#include "bits/stdc++.h"
using namespace std;

typedef long long ll;
int n = 3;

int solve(int i, int mask) {
    if (i == n) {
        int temp = mask;
        for (int j = 0; mask; ++j, mask /= 2) {
            if (mask & 1) {
               // Do Something here
            }
        }
        return __builtin_popcount(0);
    }
    return max(solve(i+1, mask|(1<<i)), solve(i+1, mask));
}

int main() {
  // cin >> n;
  cout << solve(0,0);
}