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<cstdio>
#include<cstdlib>
#include<cmath>
#include<cstring>
#include<iostream>
#include<algorithm>
#include<queue>
#include<map>
#include<set>
#include<vector>
#include<stack>
#include<list>

typedef long long ll;

using namespace std;

static const int MAX = 100010;
static const int NIL = -1;

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

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

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

int main(){
	ios::sync_with_stdio(false);
	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);
	}
	
	assign();
	

	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 <stdio.h>
#include <string.h>
#define N 100010
int father[N], root[N];
int findfather(int x){
    if(root[x]) return father[x];
    else return findfather(father[x]);
}
int main(){
    int n, m;
    scanf("%d %d", &n, &m);
    for(int i = 0; i < n; i++) {
        father[i] = i; root[i] = 1;
    }
    for(int k = 0; k < m; k++){
        int a, b;
        scanf("%d %d", &a, &b);
        root[b] = 0;
        father[b] = findfather(a);
    }
    int q;
    scanf("%d", &q);
    while(q--){
        int x, y;
        scanf("%d %d", &x, &y);
        if(father[x] == father[y]) printf("yes\n");
        else printf("no\n");
    }
    return 0;
}