UVA 10050【埃筛】【set】

#include 

using namespace std;

const int N = 2e6 + 10;
int a[N], b[N];

signed main() {
  int T;
  cin >> T;
  while (T --) {
    int n;
    cin >> n;
    for (int i = 1; i <= n; i ++)
      cin >> a[i];
    for (int i = 1; i <= n; i ++)
      cin >> b[i];
    int ans = 0;
    for (int i = 30; ~i; i --) {
      ans ^= (1 << i);
      map <int, int> _1, _2;
      for (int j = 1; j <= n; j ++)
        _1[a[j] & ans] ++;
      for (int j = 1; j <= n; j ++)
        _2[b[j] & ans] ++;
      for (int j = 1; j <= n; j ++)
        if (_1[a[j] & ans] != _2[(a[j] & ans) ^ ans]) {
          ans ^= (1 << i);
          break;
        }
    }
    cout << ans << '\n';
  }
  return 0;
}

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