Submission #348955

#	Time	Username	Problem	Language	Result	Execution time	Memory
348955		ali_tavakoli	XOR Sum (info1cup17_xorsum)	C++14	18 / 100	1683 ms	8172 KiB

xorsum

//In The Name Of Allah
#include<bits/stdc++.h>
using namespace std;

typedef long long ll;
#define pb push_back
#define F first
#define S second
#pragma GCC optimize("O2")
#pragma GCC optimize("unroll-loops")

const int maxn = 1e6 + 5, mxn = 4e3 + 5;

int n, a[maxn], cnt[maxn];

void sub1()
{
	ll ans = 0;
	for(int i = 0; i < n; i++)
		for(int j = i; j < n; j++)
			ans ^= (a[i] + a[j]);
	cout << ans << '\n';
}

void sub2()
{
	ll ans = 0;
	for(int i = 0; i < n; i++)
		cnt[a[i]] ++;
	for(int i = 0; i < mxn; i++)
		for(int j = i + 1; j < mxn; j++)
			if((cnt[i] * cnt[j]) % 2)
				ans ^= (i + j);
	//cout << ans << '\n';
	for(int i = 0; i < mxn; i++)
		if((cnt[i] * (cnt[i] - 1) / 2 + cnt[i]) % 2)
			ans ^= (i + i);
	cout << ans << '\n';
}

int main()
{
	ios::sync_with_stdio(0);cin.tie(0);cout.tie(0);
	auto t = clock();
	cin >> n;
	for(int i = 0; i < n; i++)
		cin >> a[i];
	
	if(n <= (1e5))
		sub1();
	else
		sub2();
}

Compilation message (stderr)

xorsum.cpp: In function 'int main()':
xorsum.cpp:44:7: warning: unused variable 't' [-Wunused-variable]
   44 |  auto t = clock();
      |       ^

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