Submission #128616

#	Time	Username	Problem	Language	Result	Execution time	Memory
128616		E869120	XOR Sum (info1cup17_xorsum)	C++14	18 / 100	196 ms	22780 KiB

xorsum

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

long long N, A[1 << 20], V[1 << 20], ans;

int main() {
	scanf("%lld", &N);
	for (int i = 1; i <= N; i++) scanf("%lld", &A[i]);

	if (N <= 5000) {
		for (int i = 1; i <= N; i++) {
			for (int j = i; j <= N; j++) ans ^= (A[i] + A[j]);
		}
		printf("%lld\n", ans);
	}
	else {
		for (int i = 1; i <= N; i++) V[A[i]]++;
		for (int i = 0; i <= 5000; i++) {
			for (int j = i + 1; j <= 5000; j++) {
				if ((1LL * V[i] * V[j]) % 2LL == 1LL) ans ^= (i + j);
			}
			if ((1LL * V[i] * (V[i] + 1)) / 2LL % 2LL == 1LL) ans ^= (i + i);
		}
		printf("%lld\n", ans);
	}
	return 0;
}

Compilation message (stderr)

xorsum.cpp:3:0: warning: ignoring #pragma warning  [-Wunknown-pragmas]
 #pragma warning (disable: 4996)
 
xorsum.cpp: In function 'int main()':
xorsum.cpp:8:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%lld", &N);
  ~~~~~^~~~~~~~~~~~
xorsum.cpp:9:36: 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("%lld", &A[i]);
                               ~~~~~^~~~~~~~~~~~~~~

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