Submission #67981

#	Time	Username	Problem	Language	Result	Execution time	Memory
67981		hamzqq9	XOR Sum (info1cup17_xorsum)	C++14	100 / 100	1563 ms	40324 KiB

xorsum

#include<bits/stdc++.h>
#define st first
#define nd second
#define pb push_back
#define ppb pop_back
#define umax(x,y) x=max(x,y)
#define umin(x,y) x=min(x,y)
#define ll long long
#define ii pair<int,int>
#define iii pair<int,ii>
#define sz(x) ((int) x.size())
#define orta ((bas+son)>>1)
#define all(x) x.begin(),x.end()
#define dbgs(x) cerr<<(#x)<<" --> "<<(x)<<" "
#define dbg(x) cerr<<(#x)<<" --> "<<(x)<<endl;getchar()
#define pw(x) (1<<(x))
#define inf 1000000000000000000
#define MOD 1000000007
#define N 1000006
#define MAX 10000006
#define LOG 30
using namespace std;

int n,ans,a[N];
ii ar[2][N];

int main() {

//	freopen("input.txt","r",stdin);

	scanf("%d",&n);

	for(int i=1;i<=n;i++) {

		scanf("%d",&a[i]);

		ar[0][i-1]={a[i]&1,i};

	}

	sort(ar[0],ar[0]+n);

	for(int i=0;i<LOG;i++) {

		int cp=pw(i);
		int cpp=pw(i+1);
		int cppp=pw(i+2);

		int bas=n,son=n-1;

		bool ok=0;

		int cur=i&1;

		for(int j=0;j<n;j++) {

			while(son>=0 && ar[cur][son].st+ar[cur][j].st>cpp-1) son--;
			while(bas-1>=0 && ar[cur][bas-1].st+ar[cur][j].st>=cp) bas--;

			if(son<j) break ;

			ok^=max(0,(son-max(j,bas)+1))&1;

		}

		bas=n,son=n-1;

		for(int j=0;j<n;j++) {

			while(son>=0 && ar[cur][son].st+ar[cur][j].st>cppp-2) son--;
			while(bas-1>=0 && ar[cur][bas-1].st+ar[cur][j].st>=cpp+cp) bas--;

			if(son<j) break ;

			ok^=max(0,(son-max(j,bas)+1))&1;

		}

		if(ok) ans+=pw(i);

		int now=0;
		int oth=1^cur;

		for(int j=0;j<n;j++) if(!(a[ar[cur][j].nd]&cpp)) ar[oth][now++]=ar[cur][j];

		for(int j=0;j<n;j++) if(a[ar[cur][j].nd]&cpp) ar[oth][now++]={ar[cur][j].st+cpp,ar[cur][j].nd};

	}

	printf("%d",ans);

}

Compilation message (stderr)

xorsum.cpp: In function 'int main()':
xorsum.cpp:31:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d",&n);
  ~~~~~^~~~~~~~~
xorsum.cpp:35:8: 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: 23 / 23