D. Card Game

链接：https://www.luogu.com.cn/problem/CF1932D
https://codeforces.com/problemset/problem/1932/D
总的来说，就是把每副牌分开存储，然后如果长度是奇数，那么就从万能牌中拿过来一张；如果是偶数就不需要
判断是否是impossible？
每组对2求余之后加起来，如果比万能牌长度长就impossible
题面：

代码：

#include<iostream>
#include<vector>
#include<algorithm>
#include<math.h>
#include<sstream>
#include<string>
#include<string.h>
#include<iomanip>
#include<stdlib.h>
#include<map>
#include<queue>
#include<limits.h>
#include<climits>
#include<fstream>
#include<stack>
#include<set>
typedef long long ll;
using namespace std;

const int N = 2e5 + 10;


int main()
{
	ios::sync_with_stdio(false);
	cin.tie(0), cout.tie(0);
	string menu = "CDHS";
	int t;
	cin >> t;
	while (t--)
	{
		map<char, vector<int>>mp;
		queue<string>qq;
		int n; cin >> n;
		char swin; cin >> swin;
		string sk;
		for (int i = 0; i < 2 * n; i++)
		{
			cin >> sk;
			mp[sk[1]].push_back(sk[0] - '0');
		}
		int ptr = 0;
		int twinow = 0;
		for (map<char, vector<int>>::iterator it = mp.begin(); it != mp.end(); ++it)
		{
			sort(it->second.begin(), it->second.end());
		}
		for (map<char, vector<int>>::iterator it = mp.begin(); it != mp.end(); ++it)
		{
			if (it->first == swin)twinow = it->second.size();
			else
			{
				if (it->second.size() % 2 == 1)ptr += 1;
			}
		}
		if (twinow < ptr)cout << "IMPOSSIBLE" << endl;
		else
		{
			for (int i = 0; i < 4; i++)
			{
				if (menu[i] != swin)
				{
					for (int j = 0; j < mp[menu[i]].size(); j++)
						qq.push(string(to_string(mp[menu[i]][j]) + menu[i]));
					if (mp[menu[i]].size() % 2)
					{
						qq.push(string(to_string(mp[swin][mp[swin].size() - 1]) + swin));
						mp[swin].pop_back();
					}
				}
			}
			for (int i = 0; i < mp[swin].size(); ++i)
			{
				qq.push(string(to_string(mp[swin][i]) + swin));
			}
			while (!qq.empty())
			{
				cout << qq.front() << ' ';
				qq.pop();
				cout << qq.front() << endl;
				qq.pop();
			}
		}


	}
	return 0;
}