Xor sum

#include <bits/stdc++.h>

using namespace std;
#define int long long

// g++ <filename>.cpp -g -Wall -Wextra -DDEBUG -o <executable>

// copied from: https://codeforces.com/blog/entry/79024
// === Debug macro starts here ===

int recur_depth = 0;
#ifdef DEBUG
#define dbg(x) {++recur_depth; auto x_=x; --recur_depth; cerr<<string(recur_depth, '\t')<<"\e[91m"<<__func__<<":"<<__LINE__<<"\t"<<#x<<" = "<<x_<<"\e[39m"<<endl;}
#else
#define dbg(x)
#endif
template<typename Ostream, typename Cont>
typename enable_if<is_same<Ostream,ostream>::value, Ostream&>::type operator<<(Ostream& os,  const Cont& v){
	os<<"[";
	for(auto& x:v){os<<x<<", ";}
	return os<<"]";
}
template<typename Ostream, typename ...Ts>
Ostream& operator<<(Ostream& os,  const pair<Ts...>& p){
	return os<<"{"<<p.first<<", "<<p.second<<"}";
}

// === Debug macro ends here ===

// segment tree code from programmers handbook
int sum(vector<int> &tree, int n, int a, int b) {
    
    a += n;
    b += n;
    int s = 0;
    while (a <= b) {
        if (a % 2 == 1) s ^= tree[a++];
        if (b % 2 == 0) s ^= tree[b--];
        a /= 2;
        b /= 2;
    }
    return s;
}

// segment tree code from programmers handbook
void add(vector<int> &tree, int n, int k, int x) {
    
    k += n;
    tree[k] ^= x;
    for (k /= 2; k >= 1; k /= 2) {
        tree[k] = tree[2 * k] ^ tree[2 * k + 1];
    }
}

signed main() {
    
    int n, q;
    cin >> n >> q;

    vector<int> tree(4 * n, 0);

    for (int i = 0; i < n; i++) {
        int item;
        cin >> item;
        add(tree, n, i, item);
    }

    vector<int> sum_array(q);

    for (int i = 0; i < q; i++) {
        int a, b;
        cin >> a >> b;
        int s = sum(tree, n, a - 1, b - 1);
        sum_array[i] = s;
    }

    for (int i = 0; i < q; i++) {
        cout << sum_array[i] << "\n";
    }

    return 0;
}

Test 1

Verdict: ACCEPTED

Test 2

Verdict: ACCEPTED