UVA 459- graph connectivity

#include<iostream>
#include<cstdio>
#include<cmath>
#include<vector>
#include<algorithm>
#include<map>
#include<stack>
#include<queue>
#include<cstring>
#include<set>

using namespace std;

#define MEM(array,w) memset((array),w,sizeof((array)))


int visited[26];
int visit[26][26];

char ch;


int dfs(int i)
{
    visited[i]=1;

    for(int j=0;j<=ch-'A';j++)
    {
        if(visited[j]==0 && visit[i][j]==1)
        {
            dfs(j);
        }
    }
}


int main()
{
    int test;

    cin>>test;
    getchar();


bool f=0;

    while(test--)
    {
        if(f==1)cout<<endl;f=1;
        cin>>ch;

        getchar();

        MEM(visit,0);

        memset(visited,0,sizeof(visited));

        while(1)
        {
            string s;
            getline(cin,s);

            if(s.size()==0)break;

            visit[(s[0]-'A')][(s[1]-'A')]= 1;
            visit[(s[1]-'A')][(s[0]-'A')]= 1;

        }
       int sum=0;

        for(int i=0;i<=(ch-'A');i++){

            if(visited[i]!=1){dfs(i);sum++;}
        }
        cout<<sum<<endl;
    }
    return 0;
}