Go: package main

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

const MaxNode int = 1e5

var graph [][] int
var color []int
var N int

func bfs(u, c int) {
	l := list.New()
	l.PushBack(u)
	for ;l.Len()!=0; {
		u = l.Front().Value.(int)
		color[u] = c
		l.Remove(l.Front())
		for i:=0; i<len(graph[u]); i++ {
			if color[graph[u][i]] == 0 {
				l.PushBack(graph[u][i])
			}
		}
	}
}

func assignColor() {
	id := 1
	for u:=0; u<N; u++ {
		if color[u] == 0 {
			bfs(u, id)
			id ++
		}
	}
}

func nextInt(scanner *bufio.Scanner) int {
	scanner.Scan()
	num, _ := strconv.Atoi(scanner.Text())
	return num
}


func buildGraph(scanner *bufio.Scanner) {
	N = nextInt(scanner)
	color = make([]int, N)
	graph = make([][]int, N)
	m := nextInt(scanner)
	for i:=0; i<m; i++ {
		n1 := nextInt(scanner)
		n2 := nextInt(scanner)
		graph[n1] = append(graph[n1], n2)
		graph[n2] = append(graph[n2], n1)
	}
}

func answer(scanner *bufio.Scanner) {
	var outBuffer bytes.Buffer
	cnt := nextInt(scanner)
	for i:=0; i<cnt; i++ {
		n1 := nextInt(scanner)
		n2 := nextInt(scanner)
		if color[n1] == color[n2] {
			outBuffer.WriteString("yes\n")
		} else {
			outBuffer.WriteString("no\n")
		}
	}
	fmt.Printf("%s", outBuffer.String())
}

func main() {
	scanner := bufio.NewScanner(os.Stdin)
	scanner.Split(bufio.ScanWords)
	buildGraph(scanner)
	assignColor()
	answer(scanner)
}

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;
    }
}