C题
#include <bits/stdc++.h> using namespace std; int t, n; int main() { ios::sync_with_stdio(false); cin.tie(0), cout.tie(0); cin >> t; while (t--) { cin >> n; map<int, int> mp; for (int i = 0; i < n; i++) { int x; cin >> x; mp[x]++; } int ans = 0; for (auto it : mp) { int t = it.second; if (t % 2 == 0) ans += 2; else ans += 1; } cout << ans << endl; } return 0; }