Submission #358910

#	Time	Username	Problem	Language	Result	Execution time	Memory
358910		ogibogi2004	XOR Sum (info1cup17_xorsum)	C++14	0 / 100	918 ms	35564 KiB

xorsum

#include<bits/stdc++.h>
using namespace std;
const int MAXN=4e6+6;
const int logN=21;
int n,ans;
int a[MAXN];
int pref[2][MAXN];
int main()
{
	cin>>n;
	for(int i=1;i<=n;i++)
	{
		cin>>a[i];
	}
	for(int j=0;j<logN;j++)
	{
		//cout<<j<<endl;
		memset(pref,0,sizeof(pref));
		for(int i=1;i<=n;i++)
		{
			if(a[i]&(1<<j))
			{
				pref[1][a[i]%(1<<j)]++;
			}
			else
			{
				pref[0][a[i]%(1<<j)]++;
			}
		}
		for(int j=1;j<MAXN;j++)
		{
			pref[0][j]+=pref[0][j-1];
			pref[1][j]+=pref[1][j-1];
		}
		int cnt=0;
		for(int i=1;i<=n;i++)
		{
			int t=a[i]%(1<<j);
			if(a[i]&(1<<j))
			{
				if((1<<j)-t-1>=0)cnt+=pref[0][(1<<j)-t-1];
				cnt+=pref[1][MAXN-1]-pref[1][(1<<j)-t-1];
			}
			else
			{
				if((1<<j)-t-1>=0)cnt+=pref[1][(1<<j)-t-1];
				cnt+=pref[0][MAXN-1]-pref[0][(1<<j)-t-1];
			}
			if((a[i]*2)&(1<<j))cnt++;
		}
		if((cnt/2)%2==1)ans+=(1<<j);
	}
	cout<<ans<<endl;
return 0;
}

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