Submission #1149484

#	Time	Username	Problem	Language	Result	Execution time	Memory
1149484		KluydQ	XOR Sum (info1cup17_xorsum)	C++20	100 / 100	709 ms	21916 KiB

xorsum

#include <bits/stdc++.h>
 
#define respagold ios_base::sync_with_stdio(0), cin.tie(0);
#define ll 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 = 2e9;
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 );
}
vector <int> v, v1, v0;

bool cmp( int i1, int i2 )
{
	return a[i1] < a[i2];
}
void solve()
{
	cin >> n;
	
	FOR( i, 1, n, 1 ) cin >> b[i];
	
	FOR( k, 0, 30, 1 )
	{
		FOR( i, 1, n, 1 ) a[i] = b[i] & ( (1 << k + 1) - 1 );
		
		if( k == 0 )
		{
			FOR( i, 1, n, 1 ) v.pb(i);
			sort( all( v ), cmp );
		}
		else
		{
			v1.clear(), v0.clear();
			
			for( auto i : v )
			{
				if( (a[i] >> k) & 1 ) v1.pb(i);
				else v0.pb(i);
			}
			v.clear();
			
			for( auto i : v0 ) v.pb(i);
			for( auto i : v1 ) v.pb(i);
		}
		w = 0;
		FOR( i, 1, n, 1 ) a[i] = b[v[i - 1]] & ( (1 << k + 1) - 1 );
		
		int u1 = n, u2 = n, u3 = n;
		ll ans = 0;
		
		FOR( i, 1, n, 1 )
		{
		
			while( a[u1] + a[i] >= (1 << k) && u1 > 0 ) u1 --;
			while( a[u2] + a[i] >= (1 << (k + 1)) && u2 > 0 ) u2 --;
			while( a[u3] + a[i] >= (1 << (k + 1)) + (1 << k) && u3 > 0 ) u3 --;
			
			ans += u2 - u1;
			ans += n - u3;
		}
		FOR( i, 1, n, 1 ) if( (1 << k) & (a[i] * 2) ) ans ++;
		ans /= 2;
		
		if( ans % 2 ) x += ( 1 << k );
	}
	cout << x;
}
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: 7 / 7
• Subtask 2: 11 / 11
• Subtask 3: 21 / 21
• Subtask 4: 38 / 38
• Subtask 5: 23 / 23