Submission #337778

#	Time	Username	Problem	Language	Result	Execution time	Memory
337778		nandonathaniel	XOR Sum (info1cup17_xorsum)	C++14	45 / 100	1697 ms	12780 KiB

xorsum

#include<bits/stdc++.h>
using namespace std;
const int MAXN=1e6+5;
int a[MAXN],b[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];
	}
	for(int i=0;i<29;i++){
		for(int j=1;j<=n;j++)b[j]=a[j]&((1<<(i+1))-1);
		sort(b+1,b+n+1);
//		for(int j=1;j<=n;j++)cout << b[j] << " ";
//		cout << '\n';
		int ret=0;
		for(int j=1;j<=n;j++){
			int ki=j,ka=n,res=-1;
			while(ki<=ka){
				int mid=(ki+ka)/2;
				if(b[j]+b[mid]>=(1<<i)){
					res=mid;
					ka=mid-1;
				}
				else ki=mid+1;
			}
			int awalkel2,awalkel3,awalkel4;
			if(res!=-1){
				if(b[j]+b[res]<(1<<(i+1))){
					awalkel2=res;
					ki=res+1;ka=n;res=-1;
					while(ki<=ka){
						int mid=(ki+ka)/2;
						if(b[j]+b[mid]>=(1<<(i+1))){
							res=mid;
							ka=mid-1;
						}
						else ki=mid+1;
					}
					if(res!=-1){
						if(b[j]+b[res]<=(3*(1<<i))-1){
							awalkel3=res;
							ki=res+1;ka=n;res=-1;
							while(ki<=ka){
								int mid=(ki+ka)/2;
								if(b[j]+b[mid]>=3*(1<<i)){
									res=mid;
									ka=mid-1;
								}
								else ki=mid+1;
							}
							if(res!=-1){
								awalkel4=res;
								if((awalkel3-awalkel2+n-awalkel4+1)&1)ret^=(1<<i);
							}
							else{
								if((awalkel3-awalkel2)&1)ret^=(1<<i);
							}
						}
						else{
							awalkel4=res;
							if((n+1-awalkel2)&1)ret^=(1<<i);
						}
					}
					else{
						if((n+1-awalkel2)&1)ret^=(1<<i);
					}
				}
				else if(b[j]+b[res]<=(3*(1<<i))-1){
					awalkel3=res;
					ki=res+1;ka=n;res=-1;
					while(ki<=ka){
						int mid=(ki+ka)/2;
						if(b[j]+b[mid]>=3*(1<<i)){
							res=mid;
							ka=mid-1;
						}
						else ki=mid+1;
					}
					if(res!=-1){
						awalkel4=res;
						if((n-awalkel4+1)&1)ret^=(1<<i);
					}
				}
				else{
					awalkel4=res;
					if((n-awalkel4+1)&1)ret^=(1<<i);
				}
			}
		}
		ans+=ret;
	}
	cout << ans << '\n';
	return 0;
}

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