Spoj Prayatna PR

#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define test int t; cin>>t; for(int cs=1;cs<=t;cs++)
vector<ll>graph[100005];
bool visit[100005];

void dfs(ll x)
{
    visit[x]=1;
    for(ll i=0;i<graph[x].size();i++)
    {
        ll nx=graph[x][i];
        if(visit[nx]==0)
        {
            dfs(nx);
        }
    }
}

int main()
{
   ios_base::sync_with_stdio(0);
   cin.tie(0);cout.tie(0);

   test
   {

       memset(visit,0,sizeof(visit));
       memset(graph,0,sizeof(graph));

       ll n,m,a,c,d,e,i,j,k,l=0;

       cin>>n>>m;
       for(i=0;i<m;i++)
       {
           cin>>a>>c;
           graph[a].push_back(c);
           graph[c].push_back(a);
       }

       for(i=0;i<n;i++)
       {
           if(visit[i]==0)
           {
               l++;
               dfs(i);
           }
       }
       cout<<l<<endl;
   }

   return 0;
}