Breadth First Search (aizu)

#include<bits/stdc++.h>
using namespace std;
typedef long long  ll;
const ll N=1000000;
vector<ll>adj[N+10];
bool vis[N+100];
ll  n,m;
ll level[N+1];
void BFS(ll s)
{
    vis[s]=true;

    level[s]=0;

    queue<ll>q;

    q.push(s);


    while(!q.empty())
    {
        ll u=q.front();
        q.pop();

       for(ll i=0;i<adj[u].size();i++)
       {

           if(vis[adj[u][i]]==false)
           {
               level[adj[u][i]]=level[u]+1;
               vis[adj[u][i]]=true;
               q.push(adj[u][i]);

           }


       }

    }


}

int main()
{

    cin>>n;
    ll r,c,size_of_cum;
    for(ll i=1;i<=n;i++)
    {
        cin>>r;
        cin>>size_of_cum;

      while(size_of_cum--)
      {
          cin>>c;
          adj[r].push_back(c);

      }
    }


     BFS(1);

     for(ll i=1;i<=n;i++)
     {

         if(level[i]!=0 or i==1)cout<<i<<" "<<level[i]<<endl;
         else cout<<i<<" "<<-1<<endl;

     }


}