oj.uz

Submission #357681

# Submission time Handle Problem Language Result Execution time Memory
357681 2021-01-24T12:30:42 Z Mlxa XOR Sum (info1cup17_xorsum) C++14
100 / 100
 755 ms 31212 KB 
#ifdef LC
#include "pch.h"
#else
#include <bits/stdc++.h>
#endif
using namespace std;
using ll = long long;
#define int ll
#define all(x) x.begin(), x.end()
#define x first
#define y second
#define mp make_pair
#define mt make_tuple

/*
bit = 0
oth = 1 && carry = 0
OR
oth = 0 && carry = 1

bit = 1
oth = 0 && carry = 0
OR
oth = 1 && carry = 1
*/

int solve(int a[], int an, int b[], int bn, int msk, bool carry) {
	int answer = 0;
	int j = 0;
	for (int i = an; i--; ) {
		while (j < bn && (a[i] & msk) + (b[j] & msk) <= msk) {
			++j;
		}
		if (!carry) {
			answer += j;
		} else {
			answer += bn - j;
		}
	}
	return answer;
}

const int N = 1e6 + 10;

int n;
int a[N];
int bs[2];
int b[2][N];

signed main() {
#ifdef LC
	assert(freopen("input.txt", "r", stdin));
#endif
	ios::sync_with_stdio(0); cin.tie(0);

	cin >> n;
	for (int i = 0; i < n; ++i) {
		cin >> a[i];
	}
	int answer = 0;
	for (int l = 0; l < 30; ++l) {
		// cout << "l = " << l << endl;
		// for (int i = 0; i < n; ++i) {
		// 	cout << ((a[i] >> l) & 1) << " " << (a[i] & ((1 << l) - 1)) << endl;
		// }
		// cout << "---" << endl;
		int msk = (1 << l) - 1;
		bs[0] = bs[1] = 0;
		for (int i = 0; i < n; ++i) {
			int bit = (a[i] >> l) & 1;
			b[bit][bs[bit]++] = a[i];
		}
		copy_n(b[0], bs[0], a);
		copy_n(b[1], bs[1], a + bs[0]);
		int ones = 0;
		for (int i = 0; i < n; ++i) {
			if (((a[i] + a[i]) >> l) & 1) {
				++ones;
			}
		}
		ones += solve(b[0], bs[0], b[0], bs[0], msk, true);
		ones += solve(b[0], bs[0], b[1], bs[1], msk, false);
		ones += solve(b[1], bs[1], b[0], bs[0], msk, false);
		ones += solve(b[1], bs[1], b[1], bs[1], msk, true);
		assert(ones % 2 == 0);
		ones /= 2;
		if (ones % 2) {
			answer ^= 1 << l;
		}
	}
	cout << answer << endl;
	return 0;
}

Subtask #1
7.0 / 7.0

# Verdict Execution time Memory Grader output
1 Correct 4 ms 620 KB Output is correct
2 Correct 4 ms 492 KB Output is correct

Subtask #2
11.0 / 11.0

# Verdict Execution time Memory Grader output
1 Correct 461 ms 26564 KB Output is correct
2 Correct 416 ms 24812 KB Output is correct

Subtask #3
21.0 / 21.0

# Verdict Execution time Memory Grader output
1 Correct 461 ms 26564 KB Output is correct
2 Correct 416 ms 24812 KB Output is correct
3 Correct 533 ms 28600 KB Output is correct
4 Correct 514 ms 27756 KB Output is correct

Subtask #4
38.0 / 38.0

# Verdict Execution time Memory Grader output
1 Correct 4 ms 620 KB Output is correct
2 Correct 4 ms 492 KB Output is correct
3 Correct 86 ms 3436 KB Output is correct
4 Correct 93 ms 3436 KB Output is correct

Subtask #5
23.0 / 23.0

# Verdict Execution time Memory Grader output
1 Correct 4 ms 620 KB Output is correct
2 Correct 4 ms 492 KB Output is correct
3 Correct 461 ms 26564 KB Output is correct
4 Correct 416 ms 24812 KB Output is correct
5 Correct 533 ms 28600 KB Output is correct
6 Correct 514 ms 27756 KB Output is correct
7 Correct 86 ms 3436 KB Output is correct
8 Correct 93 ms 3436 KB Output is correct
9 Correct 742 ms 31212 KB Output is correct
10 Correct 750 ms 31212 KB Output is correct
11 Correct 755 ms 31180 KB Output is correct