答案

#include <iostream> #include <set> #include <vector> using namespace std; int main() { int C; cin >> C; for (int i = 0; i < C; i++) { int n; cin >> n; set<int> uniqueNumbers; for (int j = 0; j < n; j++) { int num; cin >> num; uniqueNumbers.insert(num); } if (uniqueNumbers.size() < 2) { cout << "NO" << endl; } else { auto it = uniqueNumbers.begin(); ++it; // 移动到第二个元素 cout << *it << endl; } } return 0; }