Go: package main

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

const MAX = 100000

type Queue struct {
	head      int
	tail      int
	container [MAX]int
}

func (q *Queue) push(n int) {
	q.container[q.tail] = n
	q.tail = (q.tail + 1) % MAX
}

func (q *Queue) pop() int {
	res := q.container[q.head]
	q.head = (q.head + 1) % MAX
	return res
}

func (q *Queue) isEmpty() bool {
	return q.head == q.tail
}

var sc = bufio.NewScanner(os.Stdin)
var route [][]int
var SEEN [MAX]bool
var GROUP [MAX]int

func scanInt() int {
	num, _ := strconv.Atoi(scanString())
	return num
}

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

func init() {
	sc.Split(bufio.ScanWords)
}

func bfs(start, group int) {
	que := Queue{}
	que.push(start)

	for !que.isEmpty() {
		id := que.pop()

		if SEEN[id] {
			continue
		}
		SEEN[id] = true
		GROUP[id] = group

		for _, next := range route[id] {
			que.push(next)
		}
	}
}

func main() {
	n, m := scanInt(), scanInt()
	route = make([][]int, n)
	for i := 0; i < m; i++ {
		s, t := scanInt(), scanInt()
		route[s] = append(route[s], t)
		route[t] = append(route[t], s)
	}

	for i := 0; i < n; i++ {
		if !SEEN[i] {
			bfs(i, i+1)
		}
	}

	w := bufio.NewWriter(os.Stdout)
	q := scanInt()
	for i := 0; i < q; i++ {
		s, t := scanInt(), scanInt()
		if GROUP[s] == GROUP[t] {
			fmt.Fprintln(w, "yes")
		} else {
			fmt.Fprintln(w, "no")
		}
	}
	w.Flush()
}

C++: // Ref : https://book.mynavi.jp/ec/products/detail/id=35408

#include <iostream>
#include <vector>
#include <stack>

using namespace std;
static const int NMAX = 100000;
static const int NIL = -1;

int n, group[NMAX];
vector<int> G[NMAX];

void depthFirstSearch(int ix, int id) {
	int y;
	stack<int> S;
	S.push(ix);
	while (!S.empty()) {
		ix = S.top(); S.pop();
		for (unsigned int j = 0; j < G[ix].size(); j++) {
			y = G[ix][j];
			if (group[y] == NIL) {
				group[y] = id;
				S.push(y);
			}
		}
	}
}

void classifyID() {
	int id = 0;
	for (int i = 0; i < n; i++) {
		if (group[i] == NIL) {
			depthFirstSearch(i, id);
			id++;
		}
	}
}

int main(void) {
	int m, x, y;

	cin >> n >> m;
	for (int i = 0; i < n; i++) group[i] = NIL; // initialize group list
	for (int i = 0; i < m; i++) { // create graph in linked list representation
		cin >> x >> y;
		G[x].push_back(y);
		G[y].push_back(x);
	}

	classifyID();

	cin >> n;

	for (int i = 0; i < n; i++) {
		cin >> x >> y;
		if ((group[x] != NIL) && (group[y] != NIL) && (group[x] == group[y]))
			cout << "yes";
		else
			cout << "no";
		cout << 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;
	if(d[a]!=d[b]){
		int k=d[b];
		for(int h=0;h<n;h++){
			if(d[h]==k){
				d[h]=d[a];
			}
		}
		
		
	}
}
cin>>q;
for(int y=0;y<q;y++){
	int a,b;
	cin>>a>>b;
	if(d[a]==d[b]){
		cout<<"yes"<<endl;
	}
	else{
		cout<<"no"<<endl;
	}
}
	return 0;
}

C++: #include <iostream>
#include <vector>
#define N 100000
#define white 0

int color[N], n, S[N];
std::vector<int> c[N];



void tansaku_2(int a, int b) {
    int i, t, co, u;
    S[0] = a;
    t = 0;
    co = 1;
    while (1) {
        u = S[t];
        for (i = 0; i < c[u].size(); ++i) {
            if (color[c[u][i]] == white){
                color[c[u][i]] = b;
                S[co++] = c[u][i];
            }
        }
        S[t++] = 0;
        if (t == co) break;
    }
}

void tansaku() {
    int i, d;
    d = 1;
    
    for (i = 0; i < n; ++i) {
        if (color[i] == white) {
            color[i] = d;
            tansaku_2(i , d++);
        }
    }
}

int main() {
    int m, q, i, a, b;
    
    scanf("%d %d", &n, &m);
    for (i = 0; i < n; ++i) {
        color[i] = white;
    }
    for (i = 0; i < m; ++i) {
        scanf("%d %d", &a, &b);
        c[a].push_back(b);
        c[b].push_back(a);
    }
    tansaku();
    
    scanf("%d", &q);
    for (i = 0; i < q; ++i) {
        scanf("%d %d", &a, &b);
        if (color[a] == color[b]) {
            printf("yes\n");
        }
        else{
            printf("no\n");
        }
    }
    return 0;
}

C++: /** ???????????????, ??¢??°?????¨??? **/
#include <iostream>
#include <string>
#include <sstream>
#include <algorithm>
#include <vector>
#include <utility>
#include <functional>
#include <stack>
#include <queue>
#include <map>
#include <set>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <cmath>
#include <deque>
#include <ctime>

using namespace std;

#define rep(i,n) REP(i,0,n)
#define REP(i,s,e) for(int i=(s); i<(int)(e); i++)
#define pb push_back
#define mp make_pair
#define all(r) (r).begin(),(r).end()
#define rall(r) (r).rbegin(),(r).rend()
#define fi first
#define se second
#define ARRAY_LENGTH(array) (sizeof(array) / sizeof(array[0]))


typedef long long ll;
typedef vector<int> vi;
typedef vector<ll> vl;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;

const int INF = 1e9;
const ll LINF = 1e18;
const ll MOD = 1e9 + 7;
double EPS = 1e-8;
const double PI = acos(-1);

int dx[]={-1,1,0,0};
int dy[]={0,0,-1,1};

// ?????\?????????
// ?????°:?????????????´???°, ??????
// ???????????°????????§?????????????????´?£????????????´??????
// Down: ??????, Up: ??????
void insertionSortDown(int *a, int N){
    for(int i=1; i<N; i++){
        //???????????????,???????????????????´?????????????????????¨??????
        int v = a[i];
        int j = i - 1;

        //????????????????????¨?????¨??????????????????. ?????´??????????????????.
        while(j >= 0 && a[j] > v){
            a[j+1] = a[j];
            j--;
        }
        a[j+1] = v;

        /**
        cout << to_string(i) << "??????" << endl;
        for(int k=0; k<N; k++){
            cout << a[k] << endl;
        }
         **/
    }
}

void insertionSortUp(int *a, int N){
}

// ??????????????????
// ???????????´?£????????????´??????. ?????????????????°return?????????int???????????´??????
void bubbleSortUp(int *a, int N){
    int sw = 0;
    int flag = 1;

    while(flag == 1){
        flag = 0;

        for(int j=N-1; j>=sw; j--){
            if(a[j-1] > a[j]){
                swap(a[j-1], a[j]);
                flag = 1;
            }
        }
        sw++;
        //???????????´???????????????????????¨????????¨???????????£??????????????§.
    }
}

void selectionSortUp(int *a, int N){
    for(int i=0; i<N-1; i++){
        int minj = i;

        for(int j=i; j<N; j++){
            if(a[minj] > a[j]){
                minj = j;
            }
        }
        swap(a[minj], a[i]);
        //???????????´??§??????????????°??????????????????????????????,???????°????????????????????´???¨??????????????????
    }
}

// ?????¢??¢?´¢ O(nq)
// ??????, ?????????????´???°, ?????????????????????
bool linearSearch(int *a, int n,int key){
    int i = 0;
    a[n] = key; //??????????????????????????????

    while(a[i] != key) i++;

    //????´?????????????????????§??????????????°true?????????
    return i != n;
}


#define V_MAX 100000
#define NIL -1

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

void dfs(int u, int c){

    stack<int> S;
    S.push(u);
    color[u] = c;

    while(!S.empty()){

        int l = S.top(); S.pop();

        for(int i=0; i<G[l].size(); i++){
            int v = G[l][i];
            if(color[v] == NIL){
                color[v] = c;
                S.push(v);
            }
        }
    }
}

void assignColor(){
    for(int i=0; i<n; i++) color[i] = NIL;

    int id = 1;

    for(int j=0; j<n; j++){
        if(color[j] == NIL) dfs(j, id++);
    }

}

int main(){

    int r;
    cin >> n >> r;

    for(int i=0; i<r; i++){
        int from, to;
        cin >> from >> to;
        G[from].pb(to);
        G[to].pb(from);
    }

    assignColor();

    int q;
    cin >> q;

    int s, t;

    for(int j=0; j<q; j++){
        cin >> s >> t;
        if(color[s] == color[t]) cout << "yes" << endl;
        else cout << "no" << endl;
    }
}