bzoj3687 简单题

# include <bitset>
# include <stdio.h>
# include <string.h>
# include <algorithm>
// # include <bits/stdc++.h>

using namespace std;

typedef long long ll;
typedef long double ld;
typedef unsigned long long ull;
const int M = 5e5 + 10;
const int mod = 1e9+7;

# define RG register
# define ST static

int n, x, ans;
bitset<2000010> bs;

int main() {
    scanf("%d", &n);
    bs[0] = 1;
    for (int i=1; i<=n; ++i) {
        scanf("%d", &x);
        bs = (bs << x) ^ bs;
    }
    for (int i=0; i<=2000000; ++i)
        if(bs[i]) ans ^= i;
    printf("%d\n", ans);
    return 0;
}