bzoj3678 简单题

<pre name="code" class="cpp">/**************************************************************
Problem: 3687
User: Clare
Language: C++
Result: Accepted
Time:4968 ms
Memory:1932 kb
****************************************************************/

#include <cstdio>
#include <iostream>
#include <algorithm>
#include <cstring>
#include <cmath>
#include <queue>
#include <vector>
#include <bitset>
using namespace std;

#define N 2000010

int n,m,Ans,sum;
bitset<N> a;

int main()
{
scanf("%d",&n);
a[0]=1;
for(int i=1;i<=n;i++)
{
int x;scanf("%d",&x);
sum+=x;
a^=(a<<x);
}
for(int i=1;i<=sum;i++)
{
if(a[i])
Ans^=i;
}
cout<<Ans<<endl;
return 0;
}