Submission #362241

#	Time	Username	Problem	Language	Result	Execution time	Memory
362241		SeDunion	XOR Sum (info1cup17_xorsum)	C++17	7 / 100	1700 ms	4460 KiB

xorsum

#include<bits/stdc++.h>
using namespace std;
using ll = long long;
const int N = 1e6 + 66;
//
// bit
// 2^bit
// a[i] %= 2^(bit+1)
// 1 <= a[i] <= 2^(bit+1)-1
// 2 <= a[i] + a[j] <= 2^(bit+2)-2
// 0010000000
// 0011111111
// 0110000000
// 0111111111
//
// 2^bit <= a[i] + a[j] <= 2^(bit+1)-1
// 2^(bit+1)+2^(bit) <= a[i] + a[j] <= 2^(bit+2)-1

const int LOG = 30;

int a[N], b[N];

int main() {
	ios_base::sync_with_stdio(0);
	cin.tie(0), cout.tie(0);
	int n;
	cin >> n;
	for (int i = 1 ; i <= n ; ++ i) cin >> a[i];
	int ans = 0;
	for (int bit = 0 ; bit < LOG ; ++ bit) {
		int parity = 0;
		for (int i = 1 ; i <= n ; ++ i) {
			b[i] = a[i] % (1 << (bit+1));
			for (int j = 1 ; j <= i ; ++ j) {
				if ((b[i] + b[j]) & (1 << bit)) {
					parity ^= 1;
				}
			}
		}
		ans += parity * (1 << bit);
	}
	cout << ans;
}

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