Go: package main

import (
	"bufio"
	"container/list"
	"fmt"
	"os"
	"strconv"
)

//util
var sc = bufio.NewScanner(os.Stdin)

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

func nextInt() int {
	sc.Scan()
	i, e := strconv.Atoi(sc.Text())
	if e != nil {
		panic(e)
	}
	return i
}

func printList(list []int) {
	n := len(list)
	buf := bufio.NewWriter(os.Stdout)
	for _, v := range list[0 : n-1] {
		buf.Write([]byte(fmt.Sprintf("%d ", v)))
	}
	buf.Write([]byte(fmt.Sprintf("%d\n", list[n-1])))
	buf.Flush()
}

func max(a, b int) int {
	if a > b {
		return a
	} else {
		return b
	}
}

func min(a, b int) int {
	if a > b {
		return b
	} else {
		return a
	}
}

//solve
const (
	MAX = 100000
	NIL = -1
)

var (
	n, m, q, s, t int
	G             [MAX][]int //連結リスト
	color         [MAX]int
)

func dfs(r int, c int) {
	S := list.New()
	S.PushFront(r)
	color[r] = c
	for S.Len() != 0 {
		u := S.Remove(S.Front()).(int)
		for i := 0; i < len(G[u]); i++ {
			v := G[u][i]
			if color[v] == NIL {
				color[v] = c
				S.PushFront(v)
			}
		}
	}
}

//幅優先探索で、頂点を色付け
func assignColor() {
	id := 1
	for i := 0; i < n; i++ {
		color[i] = NIL
	}
	for i := 0; i < n; i++ {
		if color[i] == NIL {
			id++
			dfs(i, id)
		}
	}
}

func main() {
	sc.Split(bufio.ScanWords)
	n, m = nextInt(), nextInt()
	for i := 0; i < m; i++ {
		s, t = nextInt(), nextInt()
		if i == 0 {
			G[s] = make([]int, 0)
			G[t] = make([]int, 0)
		}
		G[s] = append(G[s], t)
		G[t] = append(G[t], s)

	}
	assignColor()
	q = nextInt()
	for i := 0; i < q; i++ {
		s, t = nextInt(), nextInt()
		if color[s] == color[t] {
			fmt.Println("yes")
		} else {
			fmt.Println("no")
		}
	}

}

C++: #include<iostream>
#include<vector>
#include<stack>
using namespace std;
static const int MAX = 100000;
static const int NIL = -1;

int n, color[MAX];
vector<int> G[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<iostream>
#include<string>
#include<algorithm>
#include<vector>
#include<stack>

using namespace std;

static const int MAX = 100000;
static const int NIL = -1;

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

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 = 0;
    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 m, s, t, q;

    cin >> n >> m;
    for (int i; 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 <iostream>
using namespace std;
  
int main() {
int d[100100];
int m,n,q;
cin>>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];
}
if(d[j]==j){
	while(d[h]!=h){
		h=d[h];
	}
}
else{
	while(d[j]!=j){
		j=d[j];
	}
}
d[j]=h;
d[a]=h;
d[b]=h;
}
cin>>q;
for(int y=0;y<q;y++){
    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];
}
    if(j==h){
        cout<<"yes"<<endl;
    }
    else{
        cout<<"no"<<endl;
    }
}
    return 0;
}

C++: #include<iostream>
#include<cstdio>
#include<string>
#include<algorithm>
#include<vector>
#include<cmath>
#include<map>
#include<bitset>
#include<queue>
#include<set>
#include<stack>
using namespace std;
#define FOR(i,a,b) for (int i=(a);i<(b);i++)
#define rep(i,n) FOR(i,0,n)
#define MAX 100000
typedef long long ll;
int main(){
	//連結リストを作る
	int n,m;	//user_num, relation
	cin >> n>>m;
	vector<int> G[n];

	int a,b;
	rep(i,m){
	cin >> a>>b;
	G[a].push_back(b);
	G[b].push_back(a);
	}

	//色を塗っていく
	//初期化。全て0
	int color[MAX] = {};
	int id = 1;

	rep(i,n){
	if(!color[i]) {
	
	stack<int> S;
	S.push(i);	
	color[i] = id;

	while(!S.empty()){
	int v = S.top(); S.pop();

	rep(j,G[v].size()){
	int u = G[v][j];
	if(!color[u]){
	color[u] = id;
	S.push(u);
	}
	}
	}
	}
	id++;
	}	
	
	int q,c,d;
	cin >> q;
	rep(i,q){
	cin >> c >> d;

	if (color[c]==color[d]){
	cout << "yes" << endl;
	}
	else
	cout << "no" << endl;
	}
	return 0;
}

C++: #include "bits/stdc++.h"
using namespace std;
typedef long long ll;
typedef vector<vector<int> > vvi;
typedef vector<int> vi;
typedef vector<string> vs;
typedef pair<string, int> psi;
typedef pair<int, int> pii;
#define rep(i,s,n) for(int i = (s); i < (n); i++)
#define loop(i) for(int i = 0;true; i++)
#define all(x) (x).begin(), (x).end()
#define yn(f) (f?"yes":"no")
#define YN(f) (f?"YES":"NO")
#define Yn(f) (f?"Yes":"No")
#define mn 1000000007
int main() {
	int N, M;
	cin >> N;
	cin >> M;
	vvi A(N);
	for (int i = 0; i < M; i++)
	{
		int l, r;
		scanf("%d", &l);
		scanf("%d", &r);
		A[l].push_back(r);
		A[r].push_back(l);
	}
	vi C(N, -1);
	vi v(N, 0);
	int num = 0;
	for (int i = 0; i < N; i++)
	{
		if (v[i]) {
			continue;
		}
		else {
			v[i] = 1;
			num++;
			C[i] = num;
		}
		stack<int> S;
		S.push(i);
		while (!S.empty()) {
			int temp = S.top();
			S.pop();
			for (int j = 0; j < A[temp].size(); j++)
			{
				if (v[A[temp][j]] == 0) {
					S.push(A[temp][j]);
					v[A[temp][j]] = 1;
					C[A[temp][j]] = num;
				}
			}

		}
	}
	for (int i = 0; i < N; i++)
	{
		
	}
	int k;
	cin >> k;
	for (int i = 0; i < k; i++)
	{
		int l, r;
		scanf("%d", &l);
		scanf("%d", &r);

		printf("%s\n", yn(C[l] == C[r]));
	}
};