Kosaraju’s Algorithm -Strongly Connected Component

#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define test int tt; cin>>tt; for(int cs=1;cs<=tt;cs++)
bool v[200005];
vector<ll>g[200005],g1[200005],topsort;
ll c=0;
void dfs(ll in)
{
     v[in]=1;

     for(auto d:g[in])
     {
          if(!v[d])
          {
               dfs(d);
          }
     }

     topsort.push_back(in);
}

void dfs1(ll in)
{
     v[in]=1;
     //c++;
     for(auto d:g1[in])
     {
          if(!v[d])
          {
               dfs1(d);
          }
     }
}


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

   ll n,m,i,j,k,l;

   cin>>n>>m;

   for(i=0;i<m;i++)
   {
        cin>>j>>k;
        g[j].push_back(k);
   }

   for(i=1;i<=n;i++)
   {
        if(v[i]==0)
        {
             dfs(i);
        }
   }

   memset(v,0,sizeof v);

   for(i=1;i<=n;i++)
   {
        for(auto d:g[i])
        {
             g1[d].push_back(i);
        }
   }

   for(i=topsort.size()-1;i>=0;i--)
   {
        ll u=topsort[i];
        if(v[u]==0)
        {
             c++;
             dfs1(u);
        }
   }

   cout<<"Strongly connected component "<<c<<endl;

   return 0;
}