Go: package main

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

func main() {
	var n,m int
	fmt.Scan(&n)
	group := make([]int, n)
	for i := 0; i < n; i++ {
		group[i] = i
	}
	
	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())

		if group[s] < group[t] {
			group[t] = group[s]
		} else {
			group[s] = group[t]
		}
	}

	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 root(s, &group) == root(t, &group) {
			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<vector>
#include<stack>
using namespace std;
static const int MAX = 100000;
static const int NIL = -1;

int n;
vector<int> G[MAX];
int color[MAX];

void dfs(int r, int c) {
    stack<int> S;
    S.push(r);
    color[r] = c;
    
    while(!S.empty()) {
        int u = S.top();
        S.pop();
        for(int i = 0; i < G[u].size(); i++) {
            int v = G[u][i];
            if(color[v] == NIL) {
                color[v] = c;
                S.push(v);
            }
        }
    }
}

void assignColor() {
    int id = 1;
    for(int i = 0; i < n; i++) color[i] = NIL;
    for(int u = 0; u < n; u++) {
        if(color[u] == NIL) dfs(u, id++);
    }
}

int main() {
    int s, t, m, q;
    
    cin >> n >> m;
    
    for(int i = 0; i < m; i++) {
        cin >> s >> t;
        G[s].push_back(t);
        G[t].push_back(s);
    }
    
    assignColor();
    
    cin >> q;
    
    for(int i = 0; i < q; i++) {
        cin >> s >> t;
        if(color[s] == color[t]) {
            cout << "yes" << endl;
        }else {
            cout << "no" << endl;
        }
    }
    
    return 0;
}

C++: #include <bits/stdc++.h>
using namespace std;
static const int MAX=100000;
static const int NIL=-1;

int n;
vector<int>G[MAX];
int color[MAX];

void dfs(int r,int c){
  stack <int>S;
  S.push(r);
  color[r]=c;
  while(!S.empty()){
    int u=S.top();
    S.pop();
    for(int i=0;i<G[u].size();i++){
      int v=G[u][i];
      if(color[v]==NIL){
        color[v]=c;
        S.push(v);
      }
    }
  }
}

void assignColor(){
  int id=1;
  for(int i=0;i<n;i++) color[i]=NIL;
  for(int u=0;u<n;u++){
    if(color[u]==NIL) dfs(u,id++);
  }
}

int main(){
  int s,t,m,q;
  cin>>n>>m;
  for(int i=0;i<m;i++){
    cin>>s>>t;
    G[s].push_back(t);
    G[t].push_back(s);
  }
  assignColor();
  
  cin>>q;
  for(int i=0;i<q;i++){
    cin>>s>>t;
    if(color[s]==color[t]){
      cout<<"yes"<<endl;
    }else cout<<"no"<<endl;
  }
  return 0;
}

C++: #include <bits/stdc++.h>
#define rep(i,n) for(int i = 0; i < (int)(n); i++)
#define rrep(ri,n) for(int ri = (int)(n-1); ri >= 0; ri--)
#define rep2(i,x,n) for(int i = (int)(x); i < (int)(n); i++)
#define repit(itr,x) for(auto itr = x.begin(); itr != x.end(); itr++)
#define rrepit(ritr,x) for(auto ritr = x.rbegin(); ritr != x.rend(); ritr++)
#define ALL(n) begin(n), end(n)
using ll = long long;
using namespace std;

int main(){
  int n, m;
  cin >> n >> m;
  vector<vector<int>> gr(n);
  rep(i, m){
    int a, b;
    cin >> a >> b;
    gr.at(a).push_back(b);
    gr.at(b).push_back(a);
  }
  vector<int> team(n, -1);
  int co = 0;
  while(co < n){
    int nx = -1;
    rep(i, n){
      if(team.at(i) == -1){
        nx = i;
        team.at(nx) = nx;
        co++;
        break;
      }
    }
    queue<int> q;
    q.push(nx);
    while(!q.empty()){
      auto now = q.front(); q.pop();
      for(auto i : gr.at(now)){
        if(team.at(i) != -1) continue;
        team.at(i) = nx;
        co++;
        q.push(i);
      }
    }
  }

  int q;
  cin >> q;
  rep(_, q){
    int a, b;
    cin >> a >> b;
    if(team.at(a) == team.at(b)) cout << "yes" << endl;
    else cout << "no" << endl;
  }
  return 0;
}