Xor sum

#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef vector <ll> vl;

int main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(0); cout.tie(0);

    ll n, i, q, b, e;
    cin >> n >> q;
    vl a(n), pre(n + 1, 0);
    for(i = 0; i < n; i++)
        cin >> a[i];
    for(i = 1; i <= n; i++)
        pre[i] = (pre[i - 1] ^ a[i - 1]);

    while(q--)
    {
        cin >> b >> e;
        cout << (pre[e] ^ pre[b - 1]) << "\n";
    }

    return 0;
}

Test 1

Verdict: ACCEPTED

Test 2

Verdict: ACCEPTED