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>
#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;
    }
}