1763A - Absolute Maximization - CodeForces Solution

#include <bits/stdc++.h>

typedef long long ll;

using namespace std;

int main() {
#ifdef _DEBUG
    freopen("input.txt", "r", stdin);
//	freopen("output.txt", "w", stdout);
#endif
    ios::sync_with_stdio(false);
    cin.tie(0);
    ll t;
    cin >> t;
    while (t--) {
        ll n;
        cin >> n;
        vector<ll> a(n);
        for (auto &it : a) cin >> it;

        ll ma = 0;
        ll mi = (ll) pow(2, 10) - 1;
        for (ll i = 0; i < n; ++i) {
            mi &= a[i];
            ma |= a[i];
        }
        cout << ma - mi << endl;
    }

    return 0;
}