Go: package main

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

func getScanner(fp *os.File) *bufio.Scanner {
	scanner := bufio.NewScanner(fp)
	scanner.Split(bufio.ScanWords)
	scanner.Buffer(make([]byte, 500001), 500000)
	return scanner
}

func getNextString(scanner *bufio.Scanner) string {
	scanner.Scan()
	return scanner.Text()
}

func getNextInt(scanner *bufio.Scanner) int {
	i, _ := strconv.Atoi(getNextString(scanner))
	return i
}

func main() {
	fp := os.Stdin
	if len(os.Args) > 1 {
		fp, _ = os.Open(os.Args[1])
	}

	scanner := getScanner(fp)
	writer := bufio.NewWriter(os.Stdout)

	n := getNextInt(scanner)
	m := getNextInt(scanner)
	nodes := make([]Node, n)

	for i := 0; i < n; i++ {
		nodes[i].list = make([]int, 0)
	}

	for i := 0; i < m; i++ {
		s := getNextInt(scanner)
		t := getNextInt(scanner)
		nodes[s].list = append(nodes[s].list, t)
		nodes[t].list = append(nodes[t].list, s)
	}

	c := 1
	for i := 0; i < n; i++ {
		if nodes[i].c == 0 {
			traverse(nodes, i, c)
			c++
		}
	}

	q := getNextInt(scanner)

	for i := 0; i < q; i++ {
		s := getNextInt(scanner)
		t := getNextInt(scanner)
		if nodes[s].c == nodes[t].c {
			fmt.Fprintln(writer, "yes")
			continue
		}
		fmt.Fprintln(writer, "no")
	}

	writer.Flush()
}

// Node ...
type Node struct {
	list []int
	c    int
}

func traverse(nodes []Node, r, c int) {
	nodes[r].c = c
	for _, i := range nodes[r].list {
		if nodes[i].c != 0 {
			continue
		}
		traverse(nodes, i, c)
	}
}

C++: #include <vector>
#include <iostream>
#include <stdio.h>

using namespace std;

struct UnionFind{
    vector<int> par;

    UnionFind(int N) : par(N) {
        for (int i = 0; i < N; ++i) {
            par[i] = i;
        }
    }

    int root(int x){
        if(par[x] == x) {
            return x;
        }
        return par[x] = root(par[x]);
    }

    void unite(int x, int y){

        int rx = root(x);
        int ry = root(y);
        if(rx == ry){
            return;
        }
        par[rx] = ry;
    }

    bool same(int x, int y){
        int rx = root(x);
        int ry = root(y);
        return rx == ry;
    }
};
int main(){
    int n, m;
    cin >> n >> m;
    UnionFind g(n);
    int x, y;
    for (int i = 0; i < m; ++i) {
        cin  >> x >> y;
        g.unite(x, y);
    }
    int q;
    cin >> q;
    for (int i = 0; i < q; ++i) {
        cin >> x >> y;
        if(g.same(x, y)){
            cout << "yes" << endl;
        } else {
            cout << "no" << endl;
        }
    }
    return 0;
}

C++: #include <iostream>
#include <vector>
#include <cassert>
#include <queue>

const int M = 10000000;

void connected_components(
  std::vector<std::vector<int> >& adj_list,
  std::vector<int>& component_numbers,
  int root, int current_component){
  assert(component_numbers[root] == M);

  std::queue<int> target_q;
  target_q.push(root);
  component_numbers[root] = current_component;
  // dist_q.push(0;)
  while(!target_q.empty()){
    int vtx = target_q.front(); target_q.pop();
    for(int const&  u : adj_list[vtx]){
      if(component_numbers[u] == M){
        target_q.push(u);
        component_numbers[u] = current_component;
      }
    }
  }
}

int main(int argc, char const *argv[]) {
  int n, m, q;
  std::cin >> n;
  std::cin >> m;

  std::vector<std::vector<int> > adj_list(n);

  for (size_t i = 0; i < m; i++) {
    int a, b;
    std::cin >> a;
    std::cin >> b;
    adj_list[a].push_back(b);
    adj_list[b].push_back(a);
  }

  std::vector<int> component(n, M);

  for (size_t i = 0; i < n; i++) {
    if(component[i] == M){
      connected_components(adj_list, component, i, i);
    }
  }

  std::cin >> q;

  for(size_t i =0; i < q; i++){
    int a, b;
    std::cin >> a;
    std::cin >> b;
    bool in_same_component = (component[a] == component[b]);
    std::cout << (in_same_component ? "yes" : "no") << std::endl;
  }


  return 0;
}

C++: #include <iostream>
#include <vector>
#include <vector>
#include <algorithm>
#include <stack>
#include <queue>

using namespace std;

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

int n, m, c;
vector<int> G[N];
int color[N];

void bfs(int u)
{
	queue<int> q;
	q.push(u);
	color[u] = c;

	while (!q.empty())
	{
		u = q.front(); q.pop();
		for (int i = 0; i < G[u].size(); ++i)
		{
			int v = G[u][i];
			if (color[v] == -1)
			{
				q.push(v);
				color[v] = c;
			}
		}
	}
}

void DrawColor()
{
	c = 0;
	for (int i = 0; i < n; ++i) color[i] = -1;
	for (int i = 0; i < n; ++i)
	{
		if (color[i] == -1) bfs(i);
		c++;
	}
}

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);
	}

	DrawColor();

	int n2, p1, p2;
	cin >> n2;
	for (int i = 0; i < n2; ++i)
	{
		cin >> p1 >> p2;
		if (color[p1] == color[p2])
			cout << "yes" << endl;
		else
			cout << "no" << endl;
	}

	return 0;
}

C++: #include<iostream>
#include<list>
#include<iterator>
using namespace std;

class person
{
public:
	int id;
	bool Isdone = false;
	list <person*> lis;
	bool serch(person* Per)
	{
		Isdone = true;
		for(list<person*>::iterator temp=lis.begin();temp!=lis.end();++temp)
		{
			if ((*temp) == Per)return true;
			else if ((*temp)->Isdone == true)continue;
			else
			{
				if ((*temp)->serch(Per))return true;
			}
		}
		return false;
	}
};

int main()
{
	int n, m;
	cin >> n >> m;
	person *P;
	P = new person[n];
	for (int i = 0; i < n; i++)P[i].id = i;
	for (int i = 0; i < m; i++)
	{
		int p1, p2;
		cin >> p1 >> p2;
		P[p1].lis.push_back(&P[p2]);
		P[p2].lis.push_back(&P[p1]);
	}			 
	int q;
	cin >> q;
	for (int i = 0; i < q; i++)
	{
		int p1, p2;
		cin >> p1 >> p2;
		if (P[p1].serch(&P[p2]))
		{
			cout << "yes" << endl;
		}
		else
		{
			cout << "no" << endl;
		}
		for (int l = 0; l < n; l++)P[l].Isdone = false;
	}
	delete[] P;
	return 0;
}

C++: #include <map>
#include <set>
#include <list>
#include <cmath>
#include <queue>
#include <stack>
#include <cstdio>
#include <string>
#include <vector>
#include <complex>
#include <cstdlib>
#include <cstring>
#include <numeric>
#include <sstream>
#include <iostream>
#include <algorithm>
#include <functional>
 
#define mp       make_pair
#define pb       push_back
#define all(x)   (x).begin(),(x).end()
#define rep(i,n) for(int i=0;i<(n);i++)
 
using namespace std;
 
typedef    long long          ll;
typedef    unsigned long long ull;
typedef    vector<bool>       vb;
typedef    vector<int>        vi;
typedef    vector<vb>         vvb;
typedef    vector<vi>         vvi;
typedef    pair<int,int>      pii;
 
const int INF=1<<29;
const double EPS=1e-9;
 
const int dx[]={1,0,-1,0},dy[]={0,-1,0,1};
/*
class UnionFind {
public:
	int N;
	std::vector<int> parent;
	UnionFind(int n) : N(n), parent(N, -1) {

	}
	void Union(int a, int b) {
		a = root(a);
		b = root(b);
		int sizea = size(a);
		int sizeb = size(b);
		if (sizea > sizeb) {
			int temp = b;
			b = a;
			a = temp;
		}
		parent[b] += parent[a];
		parent[a] = b;
	}
	bool Find(int a, int b) {
		return root(a) == root(b);
	}
	int root(int a) {
		if (parent[a] < 0) return a;
		return parent[a] = root(parent[a]);
	}
	int size(int a) {
		a = root(a);
		return -parent[a];
	}
};
*/

struct UnionFind {
  vector<int> data;
  UnionFind(int size) : data(size, -1) { }
  bool unionSet(int x, int y) {
    x = root(x); y = root(y);
    if (x != y) {
      if (data[y] < data[x]) swap(x, y);
      data[x] += data[y]; data[y] = x;
    }
    return x != y;
  }
  bool findSet(int x, int y) {
    return root(x) == root(y);
  }
  int root(int x) {
    return data[x] < 0 ? x : data[x] = root(data[x]);
  }
  int size(int x) {
    return -data[root(x)];
  }
};
int main(int argc, char const *argv[]) {
	int N, M;
	cin >> N >> M;
	UnionFind uf(N);
	for (int i = 0; i < M; ++i) {
		int a, b;
		cin >> a >> b;
		uf.unionSet(a, b);
	}
	int Q;
	cin >> Q;
	for (int i = 0; i < Q; ++i) {
		int a, b;
		cin >> a >> b;
		if (uf.findSet(a, b)) {
			cout << "yes" << endl;
		} else {
			cout << "no" << endl;
		}
	}

	return 0;
}