bfs new

a to b
//

#include<bits/stdc++.h>
using namespace std;
typedef long long  ll;
typedef unsigned long long ull;
#define fastread() (ios_base:: sync_with_stdio(false),cin.tie(NULL))
typedef pair<ll,ll>pll;
typedef pair<ll,pair<ll,ll>>plll;
#define fi first
#define se second
#define pb push_back
const int mod = 1e9+7;
#define fastread() (ios_base:: sync_with_stdio(false),cin.tie(NULL))
#define eb emplace_back
int X[] = {-1,0,1,1,1,0,-1,-1};
int Y[] = {-1,-1,-1,0,1,1,1,0};
//int X[] = {-1,1,0,0};
//int Y[] = {0,0,-1,1};
char a[510][510];
bool check(ll i,ll j)
{
      ll n,m;
    if(i>=0 and j>=0 and i<n and j<m)
        return true;
    else
        return false;
}
bool iset(ll n, ll k)
{
    if (n & (1ll << k))
        return true;
    else
        return false;
}
const int N=2e5+100;
vector<ll>adj[N+1];
ll n,m;
ll u,v;
bool f=true;
bool vis[N];
void bfs(ll s){
       queue<ll>q;
       q.push(s);

       while(!q.empty()){
        ll x=q.front();
        cout<<x<<endl;
        vis[x]=true;
        q.pop();
        for(ll i=0;i<adj[x].size();i++){
            if(!vis[adj[x][i]]){
                    q.push(adj[x][i]);
                    vis[adj[x][i]]=true;
            }
        }

       }



}
int main()
{
    fastread();
    cin>>n>>m;

    for(ll i=0;i<m;i++){
        cin>>u>>v;
        adj[u].pb(v);
        adj[v].pb(u);
    }

    for(ll i=0;i<n;i++){
       cout<<"node no : "<<i<<" -->";
        for(ll j=0;j<adj[i].size();j++){
         cout<<adj[i][j]<<" ";
        }cout<<endl;
    }



    while(1){
       cin>>u>>v;
       bfs(u);
       if(vis[v])cout<<"yes"<<endl;
       else cout<<"no"<<endl;
       for(ll i=0;i<=N;i++)vis[i]=false;
    }





}
/*
*/



================================
a to b with query

https://judge.u-aizu.ac.jp/onlinejudge/signin.jsp
#include<bits/stdc++.h>
using namespace std;
typedef long long  ll;
typedef unsigned long long ull;
#define fastread() (ios_base:: sync_with_stdio(false),cin.tie(NULL))
typedef pair<ll,ll>pll;
typedef pair<ll,pair<ll,ll>>plll;
#define fi first
#define se second
#define pb push_back
const int mod = 1e9+7;
#define fastread() (ios_base:: sync_with_stdio(false),cin.tie(NULL))
#define eb emplace_back
int X[] = {-1,0,1,1,1,0,-1,-1};
int Y[] = {-1,-1,-1,0,1,1,1,0};
//int X[] = {-1,1,0,0};
//int Y[] = {0,0,-1,1};
char a[510][510];
bool check(ll i,ll j)
{
      ll n,m;
    if(i>=0 and j>=0 and i<n and j<m)
        return true;
    else
        return false;
}
bool iset(ll n, ll k)
{
    if (n & (1ll << k))
        return true;
    else
        return false;
}
const int N=1e6+10;
vector<ll>adj[N+1];
ll p[N+10];
ll n,m;
ll u,v;
bool f=true;
bool vis[N];
void bfs(ll s){


       queue<ll>q;
       q.push(s);

       while(!q.empty()){
        ll x=q.front();
        //cout<<x<<endl;
        vis[x]=true;
        q.pop();
        for(ll i=0;i<adj[x].size();i++){
            if(!vis[adj[x][i]]){
            //        cout<<"in "<<x<<" "<<adj[x][i]<<" "<<p[x]<<endl;
                    q.push(adj[x][i]);
                    p[adj[x][i]]=p[x];
          //  cout<<p[adj[x][i]]<<endl;
                    vis[adj[x][i]]=true;
            }
        }

       }



}
int main()
{
    fastread();
      for(ll i=0;i<=N;i++){
        p[i]=i;
    }
    cin>>n>>m;

    for(ll i=0;i<m;i++){
        cin>>u>>v;
        adj[u].pb(v);
        adj[v].pb(u);
    }

    for(ll i=0;i<n;i++){
     //  cout<<"node no : "<<i<<" -->";
        for(ll j=0;j<adj[i].size();j++){
     //    cout<<adj[i][j]<<" ";
        }//cout<<endl;
    }


    for(ll i=0;i<n;i++){
        if(!vis[i])bfs(i);
    }


    for(ll i=0;i<n;i++){
     //   cout<<i<<" "<<p[i]<<endl;
    }


   ll q;
   cin>>q;

    while(q--){
       cin>>u>>v;
       if(p[u]==p[v])cout<<"yes"<<endl;
       else cout<<"no"<<endl;
       //for(ll i=0;i<=N;i++)vis[i]=false;
    }





}
/*
*/