Submission #391502

#	Time	Username	Problem	Language	Result	Execution time	Memory
391502		warner1129	XOR Sum (info1cup17_xorsum)	C++17	100 / 100	548 ms	20420 KiB

xorsum

#include <bits/stdc++.h>

using namespace std;

const int maxn = 1e6 + 5;

int arr[maxn], n;
int A[maxn], B[maxn], p1, p2;

int check() {
	int ret = 0;
	for (int i = 1; i <= n; i++)
		for (int j = i; j <= n; j++)
			ret ^= arr[i] + arr[j];
	return ret;
}

void solve() {
	cin >> n;
	for (int i = 1; i <= n; i++) cin >> arr[i];
	int ans = 0;
	for (int i = 0; i < 30; i++) {
		int R = (1<<i) - 1;
		p1 = p2 = 0;
		for (int j = 1; j <= n; j++)
			if ((arr[j]>>i)&1) B[++p2] = arr[j];
			else A[++p1] = arr[j];
		int ptr = p1 + 1;
		for (int j = 1; j <= p1; j++) {
			while (ptr > j && (A[j]&R) + (A[ptr-1]&R) >= (1<<i)) ptr--;
			if (ptr < j) ptr = j;
			if ((p1-ptr+1)&1) ans ^= (1<<i);
		}
		ptr = p2 + 1;
		for (int j = 1; j <= p2; j++) {
			while (ptr > j && (B[j]&R) + (B[ptr-1]&R) >= (1<<i)) ptr--;
			if (ptr < j) ptr = j;
			if ((p2-ptr+1)&1) ans ^= (1<<i);
		}
		ptr = p2;
		for (int j = 1; j <= p1; j++) {
			while (ptr && (A[j]&R)+(B[ptr]&R) >= (1<<i)) ptr--;
			if (ptr&1) ans ^= (1<<i);
		}
		for (int j = 1; j <= p1; j++) arr[j] = A[j];
		for (int j = 1; j <= p2; j++) arr[p1 + j] = B[j];
	}
	cout << ans << '\n';
}

signed main() {
	ios::sync_with_stdio(false), cin.tie(0), cout.tie(0);
	solve();
	return 0;
}

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