Submission #272197

#	Time	Username	Problem	Language	Result	Execution time	Memory
272197		theStaticMind	XOR Sum (info1cup17_xorsum)	C++14	100 / 100	1239 ms	46692 KiB

xorsum

#include<bits/stdc++.h>
#define pb push_back
#define ii pair<int,int>
#define all(x) (x).begin(),(x).end()
#define sz(x) ((int)(x).size())
#define INF 100000000000000000
#define modulo 1000000007
#define mod 998244353
//#define int long long int
using namespace std;

int32_t main(){
	ios_base::sync_with_stdio(false);
	cin.tie(NULL);

	int n, ans = 0;
	cin >> n;
	vector<int> arr(n);
	vector<ii> A;

	for(int i = 0; i < n; i++) cin >> arr[i], A.pb({0, i});

	for(int d = 0; d <= 30; d++){
		long long int w = (1ll << d);
		vector<ii> t0, t1;
		for(auto p : A){
			if(arr[p.second] & w) t1.pb({arr[p.second] % (w * 2), p.second});
			else t0.pb({arr[p.second] % (w * 2), p.second});
		}

		swap(A, t0);
		for(auto p : t1) A.pb(p);

		int p1 = n - 1, p2 = n - 1, p3 = n - 1, cnt = 0;

		for(auto p : A){
			while(p1 >= 0 && A[p1].first + p.first >= w) p1--;
			while(p2 >= 0 && A[p2].first + p.first >= 2ll * w) p2--;
			while(p3 >= 0 && A[p3].first + p.first >= 3ll * w) p3--;

			cnt += n - 1 - p3 + p2 - p1;
		}

		for(auto p : A){
			if((p.first * 2) & w) cnt++;
		}

		assert(cnt % 2 == 0);
		cnt /= 2;
		if(cnt % 2) ans |= w;
	}
	cout << ans;
}

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