bzoj3687: 简单题

 1 #include<cstdio>
 2 #include<cstdlib>
 3 #include<algorithm>
 4 #include<iostream>
 5 #include<cstring>
 6 #include<string>
 7 
 8 using namespace std;
 9 
10 void setIO(const string& a) {
11     freopen((a + ".in").c_str(), "r", stdin);
12     freopen((a + ".out").c_str(), "w", stdout);
13 }
14 
15 #include<bitset>
16 bitset<2000010> a;
17 
18 int main() {
19 #ifdef DEBUG
20     freopen("in.txt", "r", stdin);
21     freopen("out.txt", "w", stdout);
22 #endif
23     
24     int n, x, res = 0;
25     scanf("%d", &n);
26     a[0] = 1;
27     while(n--) {
28         scanf("%d", &x);
29         a ^= (a << x);
30     }
31     for(int i = 1; i <= 2000000; i++) {
32         if(a[i]) res ^= i;
33     }
34     printf("%d\n", res);
35     
36     return 0;
37 }