UVA_459_Graph Connectivity

#include<iostream>  
#include<sstream>  
#include<string>  
#include<vector>  
#include<list>  
#include<set>  
#include<map>  
#include<stack>  
#include<queue>  
#include<algorithm>  
#pragma warning(disable:4996)  
using std::cin;
using std::cout;
using std::endl;
using std::stringstream;
using std::string;
using std::vector;
using std::list;
using std::pair;
using std::set;
using std::multiset;
using std::map;
using std::multimap;
using std::stack;
using std::queue;
class DisjoinSet
{
private:
	vector<int>represent, rank;
public:
	DisjoinSet(const int &n):represent(n),rank(n)
	{
		for (int i = 0; i < n; i++)
		{
			represent[i] = i;
		}
	}
	int find(int i)
	{
		return represent[i] = represent[i] == i ? i : find(represent[i]);
	}
	void merge(const int &x, const int &y)
	{
		auto a = find(x);auto b = find(y);
		if (rank[a] < rank[b])
		{
			represent[a] = b;
		}
		else
		{
			represent[b] = a;
			if (rank[b] == rank[a])
			{
				rank[a]++;
			}
		}
	}
	int count()
	{
		set<int>ret;
		for (size_t i = 0; i < represent.size(); i++)
		{
			ret.insert(find(i));
		}
		return ret.size();
	}
};
int main()
{
	//freopen("input.txt", "r", stdin);
	//freopen("output.txt", "w", stdout);
	int T; cin >> T;
	while (T--)
	{
		char n; cin >> n; cin.get();
		DisjoinSet union_set(n - 'A'+1);
		string str;
		while (getline(cin, str))
		{
			if (str.empty())
			{
				break;
			}
			union_set.merge(str[0] - 'A', str[1] - 'A');
		}
		cout << union_set.count() << endl;
		if (T)
		{
			cout << endl;
		}
	}
	return 0;
}