Graph Connectivity

#include<bits/stdc++.h>
using namespace std;

vector<int>adj[50];
int vis[50];
void dfs(int n)
{
    vis[n]=1;
    for(int i=0; i<adj[n].size(); i++)
    {
        if(vis[adj[n][i]]==0)
            dfs(adj[n][i]);
    }
}
int main()
{
    int t;
    cin>>t;
    while(t--)
    {
        string s;
        char ch;
        cin>>ch;
        memset(vis,0,sizeof(vis));
        memset(adj,0,sizeof(adj));
        int k=ch-'A', cnt=0;
        getline(cin,s);
        while(getline(cin,s))
        {
            if(s.length()==0)
                break;
            adj[s[0]-'A'].push_back(s[1]-'A');
            adj[s[1]-'A'].push_back(s[0]-'A');
        }
        cnt=0;
        for(int i=0; i<=k; i++)
        {
            if(vis[i]==0)
            {
                cnt++;
                dfs(i);
            }
        }
        cout<<cnt<<endl;
        if(t)
            cout<<endl;
    }
    return 0;
}