Submission #1139270

#	Time	Username	Problem	Language	Result	Execution time	Memory
1139270		stdfloat	XOR Sum (info1cup17_xorsum)	C++20	7 / 100	1694 ms	4168 KiB

xorsum

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

using ll = long long;

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

	int n;
	cin >> n;

	vector<int> a(n);
	for (auto &i : a)
		cin >> i;

	int mx = *max_element(a.begin(), a.end());

	int ans = 0;
	if (mx <= (int)4e3) {
		vector<int> cnt(mx + 1);
		for (auto i : a)
			cnt[i]++;

		for (int i = 1; i <= mx; i++) {
			for (int j = 1; j <= mx; j++)
				ans ^= (((ll)cnt[i] * cnt[j]) & 1 ? i + j : 0);
		}
	}
	else {
		for (int i = 0; i < n; i++) {
			for (int j = i; j < n; j++)
				ans ^= (a[i] + a[j]);
		}
	}

	cout << ans;
}

• Subtask 1: 7 / 7
• Subtask 2: 0 / 11
• Subtask 3: 0 / 21
• Subtask 4: 0 / 38
• Subtask 5: 0 / 23