Go: package main

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

// I/O
type Scanner struct {
	sc *bufio.Scanner
}

func NewScanner() *Scanner {
	sc := bufio.NewScanner(os.Stdin)
	sc.Split(bufio.ScanWords)
	sc.Buffer(make([]byte, 1024), int(1e+9))
	return &Scanner{sc}
}

func (s *Scanner) nextStr() string {
	s.sc.Scan()
	return s.sc.Text()
}

func (s *Scanner) nextInt() int {
	i, e := strconv.Atoi(s.nextStr())
	if e != nil {
		panic(e)
	}
	return i
}

func (s *Scanner) nextFloat() float64 {
	f, e := strconv.ParseFloat(s.nextStr(), 64)
	if e != nil {
		panic(e)
	}
	return f
}

func (s *Scanner) nextRuneSlice() []rune {
	return []rune(s.nextStr())
}

func (s *Scanner) nextIntSlice(n int) []int {
	res := make([]int, n)
	for i := 0; i < n; i++ {
		res[i] = s.nextInt()
	}
	return res
}

func (s *Scanner) nextFloatSlice(n int) []float64 {
	res := make([]float64, n)
	for i := 0; i < n; i++ {
		res[i] = s.nextFloat()
	}
	return res
}

// Arithmetic
func max(nums ...int) int {
	m := nums[0]
	for _, i := range nums {
		if m < i {
			m = i
		}
	}
	return m
}

func min(nums ...int) int {
	m := nums[0]
	for _, i := range nums {
		if m > i {
			m = i
		}
	}
	return m
}

func abs(x int) int {
	if x > 0 {
		return x
	}
	return -x
}

func pow(x, y int) int {
	res := 1
	for i := 0; i < y; i++ {
		res *= x
	}
	return res
}

func ceil(a, b int) int {
	if a%b == 0 {
		return a / b
	} else {
		return a/b + 1
	}
}

// Sort
type RuneSlice []rune

func (a RuneSlice) Len() int           { return len(a) }
func (a RuneSlice) Less(i, j int) bool { return a[i] < a[j] }
func (a RuneSlice) Swap(i, j int)      { a[i], a[j] = a[j], a[i] }

// Main
func main() {
	sc := NewScanner()
	wtr := bufio.NewWriter(os.Stdout)
	N, M := sc.nextInt(), sc.nextInt()
	G := make([][]int, N)
	for i := 0; i < M; i++ {
		s, t := sc.nextInt(), sc.nextInt()
		G[s] = append(G[s], t)
		G[t] = append(G[t], s)
	}
	group := make([]int, N)
	for i := 0; i < N; i++ {
		group[i] = -1
	}
	var dfs func(cur int)
	dfs = func(cur int) {
		for i := 0; i < len(G[cur]); i++ {
			next := G[cur][i]
			if group[next] == -1 {
				group[next] = group[cur]
				dfs(next)
			}
		}
	}
	num := 0
	for i := 0; i < N; i++ {
		if group[i] == -1 {
			group[i] = num
			dfs(i)
			num++
		}
	}

	Q := sc.nextInt()
	for i := 0; i < Q; i++ {
		s, t := sc.nextInt(), sc.nextInt()
		if group[s] == group[t] {
			fmt.Fprintln(wtr, "yes")
		} else {
			fmt.Fprintln(wtr, "no")
		}
	}
	wtr.Flush()
}

C++: #include <iostream>
#include <vector>
#include <stack>
using namespace std;
#define MAX 100000
#define NIL -1
vector<int> G[MAX];
stack<int> S;
int color[MAX],n,m;
void dfs(int u,int id){
    S.push(u);
    color[u] = id;
    while(!S.empty()){
        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] = id;
                S.push(v);
            }
        }
    }
}
void dfs_init(){
    int id = 0;
    for(int i=0;i<n;i++){
        color[i] = NIL;
    }
    for(int i=0;i<n;i++){
        if(color[i]==NIL)
            dfs(i,id++);
    }

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

C++: #define _CRT_SECURE_NO_WARNINGS
#include<iostream>
#include<cstdio>
#include<string>
#include<algorithm>
#include<cmath>
#include<vector>
using namespace std;

#define REP(i,n) for(int i=0;(i)<(n);(i)++)

vector<int> adjacencyList[100005];//??£??\?????????

int n;
int color[100005];//????????????????????°?????????????±???????????????????


void assignColor() {
	REP(i, n) color[i] = -1; //?????????

	//?????????
	color[0] = 0;
	int next_index;
	REP(i, n) {
		if (color[i] == -1) color[i] = i;//????????????????????????i??§??????
		//???????????????????????????????????????????????\?????????????????????

		for (int j = 0;j < adjacencyList[i].size();j++) {
			next_index = adjacencyList[i][j]; //??£??\????????????????¬?????????????????????????
			if (color[next_index] == -1) {//??????????????????????????????i????????§??????
				color[next_index] = color[i];
			}
		}
	}
}

bool IsConCom(int s, int t) {
	//s,t???????????°?????????(???)?????????
	return color[s] == color[t];
}

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

	int s, t;
	REP(i, m) {
		cin >> s >> t;
		adjacencyList[s].push_back(t);
		adjacencyList[t].push_back(s);
	}

	assignColor();//?????????

	int q;
	cin >> q;
	REP(i, q) {
		cin >> s >> t;//s??????t?????????????????¨???????????¨???

		(IsConCom(s, t)) ? cout << "yes" : cout << "no";
		cout << endl;
	}

	return 0;
}

C++: #include <iostream>
#include <stdio.h>
using namespace std;
 
int main() {
int d[100100];
int m,n,q;
scanf("%d %d", &n,&m);
for(int i=0;i<n;i++){
    d[i]=i;
}
for(int l=0;l<m;l++){
    int a,b;
    cin>>a>>b;
    int j ,h;
    j=a,h=b;
while(d[j]!=j ||d[h]!=h){
    j=d[j];
    h=d[h];
}
d[j]=h;
while(a!=h ||b!=h){
 
    d[a]=h;
    d[b]=h;
a=d[a];
b=d[b];
}
}

scanf("%d",&q);
for(int y=0;y<q;y++){
    int a,b;
scanf("%d %d", &a,&b); 
        int j ,h;
    j=a,h=b;
while(d[j]!=j ||d[h]!=h){
    j=d[j];
    h=d[h];
}
    if(j==h){
        cout<<"yes"<<endl;
    }
    else{
        cout<<"no"<<endl;
    }
}
    return 0;
}

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;

int p[100010];

void init(int n)
{
    for(int i=0;i<n;i++)
    {
        p[i]=i;
    }
}

int fnd(int x)
{
    if(p[x]!=x)
    {
        p[x]=fnd(p[x]);
    }
    return p[x];
}

void unit(int a,int b)
{
    int fa=fnd(a),fb=fnd(b);

    if(fa!=fb)
    {
        p[fa]=fb;
    }
}

bool same(int a,int b)
{
    return fnd(a)==fnd(b);
}

int main()
{

    int n,m,q;

    cin>>n>>m;

    init(n);

    int a,b;
    for(int i=0;i<m;i++)
    {
        cin>>a>>b;
        unit(a,b);
    }

    cin>>q;

    for(int i=0;i<q;i++)
    {
        cin>>a>>b;

        if(same(a,b))
        {
            cout<<"yes"<<endl;
        }else
        {
            cout<<"no"<<endl;
        }
    }





    return 0;
}