Go: package main

import (
	"fmt"
	"bufio"
	"os"
	"strconv"
)

func main() {
	var n,m int
	fmt.Scan(&n)
	group := make([]int, n)
	g := make([][]int, n)
	for i := 0; i < n; i++ {
		g[i] = []int{}
		group[i] = -1
	}
	
	fmt.Scan(&m)
	sc := bufio.NewScanner(os.Stdin)
	sc.Split(bufio.ScanWords)
	for i := 0; i < m; i++ {
		sc.Scan()
		s, _ := strconv.Atoi(sc.Text())
		sc.Scan()
		t, _ := strconv.Atoi(sc.Text())
		
		g[s] = append(g[s], t)
		g[t] = append(g[t], s)
	}
	for i := 0; i < n; i++ {
		if group[i] != -1 {
			continue
		}
		q := []int{i}
		for len(q) > 0 {
			pop := q[0]
			if len(q) > 1 {
				q = q[1:]
			} else {
				q = []int{}
			}
			if group[pop] == -1 {
				q = append(q, g[pop]...)
				group[pop] = i
			}
		}
	}
	sc.Scan()
	q, _ := strconv.Atoi(sc.Text())
	for i := 0; i < q; i++ {
		sc.Scan()
		s, _ := strconv.Atoi(sc.Text())
		sc.Scan()
		t, _ := strconv.Atoi(sc.Text())

		if group[s] == group[t] {
			fmt.Println("yes")
		} else {
			fmt.Println("no")
		}
	}
}

func root(i int, group *[]int) int {
	if i == (*group)[i] {
		return i
	}
	(*group)[i] = root((*group)[i], group)
	return (*group)[i]
}

C++: #include <iostream>
#include <queue>
#include <cstdio>
#include <vector>
using namespace std;

int n;
void make_group(vector<int> &group, vector< vector<int> > &g) {
  bool visited[n];
  for(int i=0;i<n;i++) visited[i] = false;
  queue<int> que;
  int count = 1;
  for(int s=0;s<n;s++) {
    if(!visited[s]) {
      visited[s] = true;
      que.push(s);
      while(!que.empty()) {
        int v = que.front(); que.pop();
        group[v] = count;
        for(int i=0;i<g[v].size();i++) {
          if(!visited[g[v][i]]) {
            visited[g[v][i]] = true;
            que.push(g[v][i]);
          }
        }
      }
    }
    count++;
  }
}

int main() {
  int m,s,t,q;
  scanf("%d %d\n",&n,&m);
  vector< vector<int> > g(n);
  vector<int> group(n,0);
  for(int i=0;i<m;i++) {
    scanf("%d %d",&s,&t);
    g[s].push_back(t);
    g[t].push_back(s);
  }

  make_group(group,g);
  // cout << group << endl;
  /*
  for(int i=0;i<n;i++) {
    printf("%d:%d\n",i,group[i]);
  }
  */

  scanf("%d",&q);
  for(int i=0;i<q;i++) {
    scanf("%d %d",&s,&t);
    if(group[s] == group[t]){
      printf("yes\n");
    }
    else {
      printf("no\n");
    }
  }
}

C++: #include <cmath>
#include <cstdio>
#include <cstring>
#include <cstdlib>
#include <climits>
#include <map>
#include <list>
#include <stack>
#include <queue>
#include <vector>
#include <string>
#include <sstream>
#include <fstream>
#include <iostream>
#include <algorithm>
using namespace std;

struct node {
	int id;
	vector<int> rel;
};

int n, m, q;
node* nodes;

/* DFS * TLE! *
bool canReach(int s, int d, bool* h){
	h[s] = true;
	for(int i = 0; i < nodes[s].rel.size(); i++){
		if(nodes[s].rel[i] == d) return true;
		else if(!h[nodes[s].rel[i]]){
			if(canReach(nodes[s].rel[i], d, h)) return true;
		}
	}
	return false;
}
*/

int main() {
	scanf("%d %d", &n, &m);
	
	nodes = new node[n];
	for(int i = 0; i < n; i++){
		nodes[i].id = i;
	}
	while(m--){
		int l, r;
		scanf("%d %d", &l, &r);
		nodes[l].rel.push_back(r);
		nodes[r].rel.push_back(l);
	}
	
	scanf("%d", &q);
	while(q--){
		int l, r;
		scanf("%d %d", &l, &r);
		
		bool *h = new bool[n];
		for(int i = 0; i < n; i++){
			h[i] = false;
		}
		
		queue<int> qu;
		qu.push(l);
		while(qu.size()){
			h[qu.front()] = true;
			for(int i = 0; i < nodes[qu.front()].rel.size(); i++){
				if(nodes[qu.front()].rel[i] == r){
					puts("yes");
					goto BREAK;
				}else if(!h[nodes[qu.front()].rel[i]]){
					qu.push(nodes[qu.front()].rel[i]);
				}
			}
			qu.pop();
		}
		puts("no");
		BREAK:;
		delete[] h;
	}
	return 0;
}

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

const int INF=99999999;

vector<int> A[100000];

void get_network(int N,int M){
    int s,t;
    for(int i=0;i<M;i++){
        cin>>s>>t;
        A[s].push_back(t);
        A[t].push_back(s);
    }
}
void bfs(int n,int v,vector<int>& flag,int mark){
        queue<int> Q;
        flag[v]=mark;
        for(int i=0;i<A[v].size();i++){
                Q.push(A[v][i]);
        }
        while(!Q.empty()){
                int u=Q.front();
                flag[u]=mark;
                for(int i=0;i<A[u].size();i++){
                        if(flag[A[u][i]]==-1){
                                Q.push(A[u][i]);
                        }
                }
                Q.pop();
        }
}

int main(){
        int n,m;
        scanf("%d %d\n",&n,&m);
        get_network(n,m);

        vector<int> flag(n,-1);
        int colored=-1;
        int v=0;
        int mark=0;
        while(colored!=0){
                mark++;
                bfs(n,v,flag,mark);
                colored=0;
                for(int i=0;i<flag.size();i++){
                    if(flag[i]==-1){
                        v=i;
                        colored=1;
                        break;
                    }
                }
        }

        int q,s,t;
        scanf("%d\n",&q);

        for(int i=0;i<q;i++){
                scanf("%d %d\n",&s,&t);
                if(flag[s]==flag[t]){
                        printf("yes\n");
                }else{
                        printf("no\n");
                }
        }
        return 0;
}

C++: #include <iostream>
#include <string>
#include <stdio.h>
#include <vector>
#include <stack>
#include <queue>
#define N 100000
using namespace std;


int C[N];
queue<int> k;
vector<int> v[N];
void color(int);
bool search(int,int);

int main(){
	int n,m,a,b,q;
	cin >> n >>m;
	for(int i=0;i<m;i++){
		cin >> a >> b;
		v[a].push_back(b);
		v[b].push_back(a);
	}
	cin >> q;
	for(int i=0;i<n;i++){
		C[i]=-1; //?????????
	}
	for(int i=0;i<n;i++){
		if(C[i]==-1)color(i); //i????§??????¨????????±???
	}
	for(int i=0;i<q;i++){
		cin>>a>>b;
		if(search(a,b)) cout<<"yes"<<endl;
		else cout<<"no"<<endl;
	}
	return 0;
}

bool search(int a,int b){
	if(C[a]==C[b]) return true;
	else return false;
}

void color(int a){
	static int c=0;
	c++;
	C[a]=c;
	k.push(a);
	while(!k.empty()){
		int m = k.front();
		k.pop();
		for(int i=0;i<v[m].size();i++){
			int Z= v[m].at(i);
			if(C[Z]==-1){
				C[Z]=c;
				k.push(Z);
			}
		}
	}
}

C++: #include<iostream>
#include<cstdio>
#include<cstdlib>
#include<string.h>
#include<stack>
#include<queue>
#include<vector>
using namespace std;

int n, m;
int d[100000];
int t = 0;
int c[100000];
queue<int> q;
vector<int> v[100000];
int ans = 2;

void bfs(int u){
  q.push(u);
  c[u] = 1;

  while(q.empty() == 0){
    u = q.front();
    q.pop();
    for(int i = 0; i < v[u].size(); i++){
      if(c[v[u][i]] == 0){
        q.push(v[u][i]);
        c[v[u][i]] = 1;
      }

    }
    c[u] = ans;
  }

}


int main(){

  cin >> n;

  for(int i = 0; i < n; i++){
    c[i] = 0;
  }

  cin >> m;

  for(int i = 0; i < m; i++){
    int x, y;
    cin >> x >> y;
    v[x].push_back(y);
    v[y].push_back(x);
  }

  for(int i = 0; i < n; i++){
    if(c[i] == 0){
      bfs(i);
      ans++;
    }
  }

  int q;
  cin >> q;

  for(int i = 0; i < q; i++){
    int x, y;
    cin >> x >> y;
    if(c[x] == c[y]) cout << "yes" << endl;
    else cout << "no" << endl;
  }

  return 0;
}