A2030 [蓝桥杯 2021 省 A] 异或数列

#include <bits/stdc++.h>
using namespace std;

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);

    int T;
    cin >> T;
    while (T--) {
        int n;
        cin >> n;
        vector<int> x(n);
        int s = 0;
        for (int i = 0; i < n; ++i) {
            cin >> x[i];
            s ^= x[i];
        }

        if (s == 0) {
            cout << 0 << "\n";
            continue;
        }

        int k = 0;
        while ((1 << (k + 1)) <= s) ++k;

        int cnt = 0;
        for (int i = 0; i < n; ++i)
            if (x[i] >> k & 1) ++cnt;

        if (cnt == 1 || (n & 1)) cout << 1 << "\n";
        else cout << -1 << "\n";
    }
    return 0;
}