Xor sum

#include <iostream>
#include <vector>
using namespace std;

int main() {
    int n_count, q_count, sum;
    cin >> n_count >> q_count;

    vector<int> n(n_count);
    for (int i = 0; i < n_count; i++) cin >> n[i];

    vector<vector<int>> q(q_count);
    for (int i = 0; i < q_count; i++) {
        int a, b;
        cin >> a >> b;
        q[i] = {a, b};
    };

    for (int i = 0; i < q_count; i++) {
        sum = n[q[i][0] - 1];

        for (int j = q[i][0]; j < q[i][1]; j++) {
            sum ^= n[j];
        };

        cout << sum << endl;
    };

    return 0;
}

Test 1

Verdict: ACCEPTED

Test 2

Verdict: TIME LIMIT EXCEEDED