Submission #1149433

#	Time	Username	Problem	Language	Result	Execution time	Memory
1149433		KluydQ	XOR Sum (info1cup17_xorsum)	C++20	11 / 100	77 ms	15940 KiB

xorsum

#include <bits/stdc++.h>
 
#define respagold ios_base::sync_with_stdio(0), cin.tie(0);
#define ll long long
#define int long long
#define int2 __int128_t
#define FOR( i, x, n, d ) for( int i = x; i <= n; i += d )
#define FORR( i, x, n, d ) for( int i = x; i >= n; i -= d )
#define F first
#define S second
#define all(x) x.begin(), x.end()
#define sz(x) (int)(x.size())
#define pb push_back
#define ins insert
#define lb lower_bound
#define ub upper_bound
#define pii pair <int, int>
#define mkp make_pair
 
using namespace std;
 
const int N = 1e6 + 123;
const int inf = 2e18;
const int MOD = 1e9 + 7;
const int MOD1 = 998244353;
const int P = 6547;
 
int a[N], b[N], c[N], n, m, x, y, z, w;
 
mt19937 rng( chrono::steady_clock::now().time_since_epoch().count());
 
int rand( int l, int r )
{
    uniform_int_distribution <int> uid( l, r );
    return uid( rng );
}
void solve()
{
	cin >> n;
	
	FOR( i, 1, n, 1 ) cin >> a[i], b[a[i]] ++;
	int ans = 0;
	
	if( n <= 4e3 )
	{
		FOR( i, 1, n, 1 )
		{
			FOR( j, i, n, 1 ) ans ^= ( a[i] + a[j] );
		}
	}
	else
	{
		FOR( i, 1, 4e3, 1 )
		{
			FOR( j, i, 4e3, 1 )
			{
				int cnt = ( i == j ? ( b[i] * (b[i] + 1) >> 1ll ) : b[i] * b[j] );
				if( cnt % 2 ) ans ^= ( i + j );
			}
		}
	}
	cout << ans;
}
signed main() 
{
//	freopen("connect.in", "r", stdin);
//	freopen("connect.out", "w", stdout);
	    
    respagold
    
    int test = 1;
    
    if( !test ) cin >> test;
	
	while( test -- )
	{
		solve();
	}
}
// solved by KluydQ  

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