【題目敘述】http://codeforces.com/contest/1438/problem/B
#include <iostream>
#include <map>
using namespace std;
int t, n, a;
int main() {
cin >> t;
while (t--){
cin >> n;
map <int, int> mp;
bool flag = false;
for (int i = 0; i < n; i++){
cin >> a;
if (mp[a]) flag = true;
mp[a]++;
}
if (flag) cout << "YES\n";
else cout << "NO\n";
}
}