atcoder ABC147 C問題(ビット全探索の問題)についての質問

if(bit & 1 << x[i][j])

if(bit >> x[i][j] & 1)

#include <atcoder/all>
#include <bits/stdc++.h>
#include <string>

using namespace std;
using namespace atcoder;
using ll = long long;

#define rep(i, n) for (int i = 0; i < (int)(n); i++) // 単純なfor文
#define reps(i, m, n) for (int i = (int)(m); i < (int)(n); i++) // 指定for文
#define pb push_back
#define eb emplace_back

//--------------------------------------------------//

//--------------------------------------------------//

int main() {

  //---------------text temprate--------------------//
  ifstream in("in.txt");
  if (in.is_open()) {
    cin.rdbuf(in.rdbuf());
  }
  //---------------text temprate--------------------//

  //------------------------------------------------//
  //---------------koko kara kizyutu----------------//

  int n;
  cin >> n;
  vector<int> a(n);
  vector<vector<int>> x(n), y(n);

  rep(i, n) {
    cin >> a[i];
    rep(j, a[i]) {
      int u, t;
      cin >> u >> t;
      u--;
      x[i].pb(u);
      y[i].pb(t);
    }
  }

  bool hantei;
  int ans = 0;
  rep(bit, 1 << n) {
    hantei = true;
    rep(i, n) {
      if (!(bit & (1 << i)))
        continue;

      //該当箇所ここです
      rep(j, a[i]) {
        if ((bit & (1 << x[i][j])) ^ y[i][j])
          hantei = false;
      }
    }
    if (hantei)
      ans = max(ans, __builtin_popcount(bit));
  }

  cout << ans << endl;

  //---------------koko made kizyutu----------------//
  //------------------------------------------------//
}