Submission #766162

#	Time	Username	Problem	Language	Result	Execution time	Memory
766162		Ahmed57	XOR Sum (info1cup17_xorsum)	C++17	45 / 100	1674 ms	24232 KiB

xorsum

#include <bits/stdc++.h>

using namespace std;

signed main(){
    ios_base::sync_with_stdio(false);cin.tie(0);
    long long n;
    cin>>n;
    long long arr[n];
    for(int i = 0;i<n;i++){
        cin>>arr[i];
    }
    long long all = 0;
    for(int i = 0;i<=6;i++){
        long long frq[(1<<(i+1))] = {0};
        long long cnt = 0;
        for(int j = 0;j<n;j++){
            frq[arr[j]&((1<<(i+1))-1)]++;
        }
        for(int j = 0;j<(1<<(i+1));j++){
            for(int e = j;e<(1<<(i+1));e++){
                if((j+e)&(1<<i)){
                    if(j==e)cnt+=(frq[j]*frq[e]+frq[j])/2;
                    else cnt+=frq[j]*frq[e];
                }
            }
        }
        if(cnt&1)all+=(1<<i);
    }
    for(long long i = 7;i<30;i++){
        vector<long long> v;
        long long ans = 0;
        for(int j = 0;j<n;j++){
            if((arr[j]+arr[j])&(1LL<<i)){
                ans++;
            }
            v.push_back(arr[j]&((1LL<<(i+1))-1));
        }
        sort(v.begin(),v.end());
        for(int j = 0;j<n;j++){
            long long l = (1LL<<i) , r = (1LL<<(i+1));
            l-=arr[j] , r-=arr[j];
            l&=((1LL<<(i+1))-1);
            r&=((1LL<<(i+1))-1);
            l+=(1LL<<(i+1));
            r+=(1LL<<(i+1));
            l&=((1LL<<(i+1))-1);
            r&=((1LL<<(i+1))-1);
            if(l<r){
                ans += (lower_bound(v.begin(),v.end(),r)-v.begin())-(lower_bound(v.begin(),v.end(),l)-v.begin());
            }else{
                ans += (lower_bound(v.begin(),v.end(),r)-v.begin()) + (n-(lower_bound(v.begin(),v.end(),l)-v.begin()));
            }
        }
        if(((ans/2)&1))all+=(1LL<<i);
    }
    cout<<all<<endl;
}

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