Submission #67965

#	Time	Username	Problem	Language	Result	Execution time	Memory
67965		MrTEK	XOR Sum (info1cup17_xorsum)	C++14	77 / 100	1660 ms	24368 KiB

xorsum

#include <bits/stdc++.h>

using namespace std;
#define mp make_pair
#define pb push_back
#define len(a) (int)a.size()
#define fi first
#define sc second
#define left ind + ind
#define right ind + ind + 1
#define pw(n) (1 << (n))
#define mid (l + r) / 2 
#define d1(w) cerr<<#w<<":"<<w<<endl;
#define d2(w,c) cerr<<#w<<":"<<w<<" "<<#c<<":"<<c<<endl;
#define d3(w,c,z) cerr<<#w<<":"<<w<<" "<<#c<<":"<<c<<" "<<#z<<":"<<z<<endl;
#define FAST_IO ios_base::sync_with_stdio(false);
#define endl '\n'

const int maxn = 620;
const long long LINF = 1e18;
const int LOG = 31;
const int INF = 1e9 + 5;
const int N = 1e6 + 5;
const int M = 4e3 + 5;
const int SQ = 350;
const int MOD = 998244353;

typedef pair <int,int> pii;

int n,a[N],mark[N],ans;

pii b[N],nb[N];

int main() {

	scanf("%d",&n);

	for (int i = 1 ; i <= n ; i++) {
		scanf("%d",&a[i]);
		b[i] = mp(a[i] & 1,i);
	}

	sort(b + 1, b + n + 1);
	b[n + 1] = mp(INF,0);

	memset(mark,-1,sizeof mark);

	for (int i = 0 ; i < LOG ; i++) {
		long long cnt = 0;
		int r1 = n + 1,r2 = n + 1,r3 = n + 1;
		for (int l = 1 ; l <= n ; l++) {
			while(r1 > 1 && b[l].fi + b[r1 - 1].fi >= pw(i)) r1--;
			while(r2 > 1 && b[l].fi + b[r2 - 1].fi >= pw(i + 1)) r2--;
			while(r3 > 1 && b[l].fi + b[r3 - 1].fi >= pw(i + 1) + pw(i)) r3--;
			cnt += max(0,n - r1 - (r3 - r2) + 1);
		}
		int say = 0;
		for (int j = 1 ; j <= n ; j++) if ((b[j].fi * 2) & pw(i)) say++;
		cnt = (cnt + say) / 2;
		if (cnt & 1) ans += pw(i);
		if (i < LOG - 1) {
			int last = 0;
			for (int j = 1 ; j <= n ; j++) {
				if (a[b[j].sc] & pw(i + 1)) mark[j] = i;
				else nb[++last] = b[j]; 
			}
			for (int j = 1 ; j <= n ; j++) if(mark[j] == i) nb[++last] = mp(b[j].fi + pw(i + 1),b[j].sc);
			for (int j = 1 ; j <= n ; j++) b[j] = nb[j];
		}		
	}

	printf("%d\n",ans);

	return 0;
}

Compilation message (stderr)

xorsum.cpp: In function 'int main()':
xorsum.cpp:36:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d",&n);
  ~~~~~^~~~~~~~~
xorsum.cpp:39:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d",&a[i]);
   ~~~~~^~~~~~~~~~~~

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