Kortit

#include <bits/stdc++.h>

typedef long long ll;

#define M 1000000007

using namespace std;

int main() {
	ios_base::sync_with_stdio(false);
	cin.tie(0);
	int t;
	cin >> t;
	for (int i = 0; i < t; ++i) {
		int n;
		cin >> n;
		set<int> op;
		set<int> me;

		for (int i = 1; i <= n; ++i) {
			op.insert(i);
		}

		for (int i = 0; i < n / 2; ++i) {
			int val;
			cin >> val;
			me.insert(val);
			op.erase(val);
		}

		int p = 0;
		for (int i = 0; i < n / 2; ++i) {
			auto it = op.end();
			it--;
			int opv = *it;
			op.erase(it);
			it = me.end();
			it--;
			int e = *it;
			if (e > opv) {
				me.erase(it);
				p++;
			}
			else {
				me.erase(me.begin());
			}
		}
		cout << p << endl;
	}

	return 0;
}

Test 1

Group: 1, 2

Verdict: ACCEPTED

Test 2

Group: 2

Verdict: ACCEPTED