Submission #410464

#	Time	Username	Problem	Language	Result	Execution time	Memory
410464		nichke	XOR Sum (info1cup17_xorsum)	C++14	45 / 100	1643 ms	20444 KiB

xorsum

#include <bits/stdc++.h>
using namespace std;
#define int long long
#define endl '\n'

int n, res;
int ar[1000006];
int tar[1000006];

signed main() {
	ios_base::sync_with_stdio(0);
	cin.tie(0);
	cin >> n;
	for (int i = 0; i < n; i++) {
		cin >> ar[i];
	}
	for (int j = 0; j < 31; j++) {
		for (int i = 0; i < n; i++) {
			tar[i] = ar[i] % (1 << (j + 1));
		}
		sort(tar, tar + n);
		int sum = 0;
		for (int i = 0; i < n; i++) {
			int p1, p2, p3;
			p1 = p2 = p3 = i - 1;
			int l = i, r = n - 1;
			while (l <= r) {
				int m = (l + r) / 2;
				if (tar[i] + tar[m] < (1 << j)) {
					p1 = m;
					l = m + 1;
				} else {
					r = m - 1;
				}
			}
			l = i, r = n - 1;
			while (l <= r) {
				int m = (l + r) / 2;
				if (tar[i] + tar[m] < (2 * (1 << j))) {
					p2 = m;
					l = m + 1;
				} else {
					r = m - 1;
				}
			}
			l = i, r = n - 1;
			while (l <= r) {
				int m = (l + r) / 2;
				if (tar[i] + tar[m] < (3 * (1 << j))) {
					p3 = m;
					l = m + 1;
				} else {
					r = m - 1;
				}
			}
			sum += p2 - p1 + n - p3;
		}
		if (sum & 1) res += (1 << j);
	}
	cout << res << '\n';
	return 0;
}

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