숫자 골라내기

#include<cstdio>

#include<set>

using namespace std;

int Answer;

int main(int argc, char** argv)

{

setbuf(stdout, NULL);

int T, test_case, now, n;

set<int> num;

scanf("%d", &T);

for (test_case = 0; test_case < T; test_case++)

{

Answer = -1;

scanf("%d", &n);

for (int i = 0; i < n; ++i)

{

scanf("%d", &now);

if (num.count(now))

num.erase(num.find(now));

else

num.insert(now);

}

for (set<int>::iterator iter = num.begin(); iter != num.end(); ++iter)

if (Answer == -1)

Answer = *iter;

else

Answer ^= *iter;

printf("Case #%d\n%d\n", test_case + 1, Answer);

num.clear();

}

return 0;

}