Submission #270306

#	Time	Username	Problem	Language	Result	Execution time	Memory
270306		MrTEK	XOR Sum (info1cup17_xorsum)	C++14	100 / 100	1345 ms	33232 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 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,pw[N],a[N],mark[N],ans;
 
pii b[N],nb[N];
 
int main() {
 
	scanf("%d",&n);
 
	pw[0] = 1;
 
	for (int i = 1 ; i < LOG ;i++) pw[i] = pw[i - 1] * 2;
 
	for (int i = 1 ; i <= n ; i++) {
		scanf("%d",&a[i]);
		b[i] = mp(a[i] & 1,i);
	}
 
	sort(b + 1, b + n + 1);
  
	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(r3 > 1 && b[l].fi + b[r3 - 1].fi >= pw[i + 1] + pw[i]) r3--;	
			// r2 = min(r2,r3);		
			while(r2 > 1 && b[l].fi + b[r2 - 1].fi >= pw[i + 1]) r2--;
			// r1 = min(r1,r3);
			while(r1 > 1 && b[l].fi + b[r1 - 1].fi >= pw[i]) r1--;
			cnt += 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:35:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   35 |  scanf("%d",&n);
      |  ~~~~~^~~~~~~~~
xorsum.cpp:42:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   42 |   scanf("%d",&a[i]);
      |   ~~~~~^~~~~~~~~~~~

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