Submission #338034

#	Time	Username	Problem	Language	Result	Execution time	Memory
338034		nandonathaniel	XOR Sum (info1cup17_xorsum)	C++14	100 / 100	1057 ms	30584 KiB

xorsum

#include<bits/stdc++.h>
using namespace std;
const int MAXN=1e6+5;
typedef pair<int,int> pii;
 
vector<pii> b,nol,satu;
int a[MAXN];
 
int main(){
	ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
	int n,ans=0;
	cin >> n;
	for(int i=1;i<=n;i++){
		cin >> a[i];
		b.push_back({0,i});
	}
	for(int bt=0;bt<30;bt++){
		nol.clear();
		satu.clear();
		for(int i=0;i<n;i++){
			if((1<<bt) & a[b[i].second]){
				satu.push_back({b[i].first+(1<<bt),b[i].second});
			}
			else{
				nol.push_back(b[i]);
			}
		}
		b.clear();
		for(auto isi : nol)b.push_back(isi);
		for(auto isi : satu)b.push_back(isi);
		int notkel2=n-1,notkel3=n-1,notkel4=n-1;
		long long cnt=0;
		//binser TLE, terpaksa two pointer
		for(auto isi : b){
			while(notkel2>=0 && isi.first+b[notkel2].first>=(1<<bt))notkel2--;
			while(notkel3>=0 && isi.first+b[notkel3].first>=2*(1<<bt))notkel3--;
			while(notkel4>=0 && isi.first+b[notkel4].first>=3*(1<<bt))notkel4--;
			cnt+=(n-1-notkel4+notkel3-notkel2);
		}
		for(auto isi : b){
			if((2*isi.first) & (1<<bt))cnt++;
		}
		cnt/=2;
		if(cnt&1)ans+=(1<<bt);
	}
	cout << ans << '\n';
	return 0;
}

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