Submission #128663

#	Time	Username	Problem	Language	Result	Execution time	Memory
128663		E869120	XOR Sum (info1cup17_xorsum)	C++14	100 / 100	1090 ms	106568 KiB

xorsum

#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;
#pragma warning (disable: 4996)

const int THRESHOLD = 23;

int N, A[1 << 20], S[1 << 24], V[1 << 21];
pair<int, int> U[1 << 20];
pair<int, int> U0[1 << 20];
pair<int, int> U1[1 << 20];

void making(int bit) {
	if (bit == THRESHOLD) {
		int TEISUU = (2 << bit) - 1;
		for (int i = 1; i <= N; i++) U[i - 1] = make_pair((A[i] & TEISUU), i);
		sort(U, U + N);
	}
	else {
		int c1 = 0, c2 = 0, TEISUU = (2 << bit) - 1;
		for (int i = 0; i < N; i++) {
			if ((A[U[i].second] & TEISUU) < (1 << bit)) { U0[c1] = make_pair((A[U[i].second] & TEISUU), U[i].second); c1++; }
			if ((A[U[i].second] & TEISUU) >= (1 << bit)) { U1[c2] = make_pair((A[U[i].second] & TEISUU), U[i].second); c2++; }
		}
		for (int i = 0; i < c1; i++) U[i] = U0[i];
		for (int i = 0; i < c2; i++) U[i + c1] = U1[i];
	}
	for (int i = 0; i < N; i++) V[i] = U[i].first;
	for (int i = 0; i < N; i++) V[i + N] = V[i] + (2 << bit);
}

int solve(int bit) {
	if (bit <= THRESHOLD - 1) {
		for (int i = 0; i < (4 << bit); i++) S[i] = 0;
		long long sum = 0; int TEISUU = (2 << bit);
		for (int i = 1; i <= N; i++) {
			S[A[i] & (TEISUU - 1)]++;
			S[(A[i] & (TEISUU - 1)) + TEISUU]++;
		}
		for (int i = 1; i < (4 << bit); i++) S[i] += S[i - 1];

		for (int i = 1; i <= N; i++) {
			int F = (3 << bit) - (A[i] & (TEISUU - 1)); F &= (TEISUU - 1);
			int pos1 = 0; if (F >= 1) pos1 = S[F - 1];
			int pos2 = 0; if (F + (1 << bit) >= 1) pos2 = S[(F + (1 << bit)) - 1];
			sum += 1LL * (pos2 - pos1);
		}

		long long sum2 = 0;
		for (int i = 1; i <= N; i++) {
			if (((A[i] + A[i]) & (TEISUU - 1)) >= (1 << bit)) sum2++;
		}
		return (sum2 + (sum - sum2) / 2LL) % 2LL;
	}
	else {
		making(bit); int TEISUU = (2 << bit); long long sum = 0;

		int c1 = 0, c2 = 0;
		for (int i = N - 1; i >= 0; i--) {
			int F1 = (3 << bit) - (U[i].first & (TEISUU - 1));
			int F2 = (4 << bit) - (U[i].first & (TEISUU - 1));
			while (c1 < N * 2 && V[c1] < F1) c1++;
			while (c2 < N * 2 && V[c2] < F2) c2++;
			sum += 1LL * (c2 - c1);
		}

		long long sum2 = 0;
		for (int i = 1; i <= N; i++) {
			if (((A[i] + A[i]) & (TEISUU - 1)) >= (1 << bit)) sum2++;
		}
		return (sum2 + (sum - sum2) / 2LL) % 2LL;
	}
}

int main() {
	scanf("%d", &N); int maxn = 0;
	for (int i = 1; i <= N; i++) { scanf("%d", &A[i]); maxn = max(maxn, A[i]); }

	int P = 0; for (int i = 0; i <= 30; i++) { if ((1 << i) <= maxn) P = i; }

	int ans = 0;
	for (int i = 0; i <= min(29, P + 1); i++) {
		int t = solve(i);
		if (t == 1) ans += (1 << i);
	}
	printf("%d\n", ans);
	return 0;
}

Compilation message (stderr)

xorsum.cpp:5:0: warning: ignoring #pragma warning  [-Wunknown-pragmas]
 #pragma warning (disable: 4996)
 
xorsum.cpp: In function 'int main()':
xorsum.cpp:77:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d", &N); int maxn = 0;
  ~~~~~^~~~~~~~~~
xorsum.cpp:78:38: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  for (int i = 1; i <= N; i++) { scanf("%d", &A[i]); maxn = max(maxn, A[i]); }
                                 ~~~~~^~~~~~~~~~~~~

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