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 <iostream>

using namespace std;

const int N = 100000;
int A[N][N] = {{0}};
int n;

bool dfs(int s, int t) {
    if (A[s][t] == 1) {
        return true;
    }
    for (int i = 0; i < n; ++i) {
        if (i != t && A[s][i] != 0) {
            if (dfs(i, t)) {
                return true;
            }
        }
    }
    return false;
}

int main() {
    int m;
    cin >> n >> m;
    for (int i = 0; i < m; ++i) {
        int s, t;
        cin >> s >> t;
        A[s][t] = 1;
    }

    int q;
    cin >> q;
    for (int j = 0; j < q; ++j) {
        int x, y;
        cin >> x >> y;

        if (dfs(x, y)) {
            cout << "yes";
        } else {
            cout << "no";
        }
        cout << endl;
    }

    return 0;
}

C++: #include<iostream>
#include<vector>
#include<stack>
#include<cstdio>
using namespace std;
static const int MAX = 100000;
static const int NIL = -1;
int n ;
vector<int> G[MAX];
int color [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 ass()
{
  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);
    }
  ass();
  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 <cstdio>
#include <iostream>
#include <vector>

#define N 100000

using namespace std;

vector<int> G[N];
int color[N];

void dfs(int s,int c){
  color[s]=c;
  for(int i=0;i<G[s].size();i++){
    if(color[G[s][i]]!=c) dfs(G[s][i],c);
  }
}

int main(){
  int n,m;
  scanf("%d %d",&n,&m);
  for(int i=0;i<n;i++) color[i]=-1;
  for(int i=0;i<m;i++){
    int s,t;
    scanf("%d %d",&s,&t);
    G[s].push_back(t);
    G[t].push_back(s);
  }
  int q; scanf("%d",&q);
  for(int i=0;i<n;i++){
    if(color[i]==-1)
      dfs(i,i); //node_id and color_id
  }
  for(int i=0;i<q;i++){
    int s,t;
    scanf("%d %d",&s,&t);
    if(color[s]==color[t]) cout << "yes\n";
    else cout << "no\n";
  }
}

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

using namespace std;

const int kSize = 100001;

vector<int> adj[kSize];
bool isMarked[kSize];
int d[kSize];
int cc = 0;

void dfs(int v) {
    isMarked[v] = true;
    d[v] = cc;

    for (int i = 0; i < adj[v].size(); ++i) {
        int u = adj[v][i];
        if (!isMarked[u]) {
            dfs(u);
        }
    }
}

int main() {
    int n, m;
    fill(isMarked, isMarked + kSize, false);
    cin >> n >> m;
    for (int i = 0; i < m; ++i) {
        int from, to;
        cin >> from >> to;
        adj[from].push_back(to);
        adj[to].push_back(from);
    }

    for (int i = 0; i < n; ++i) {
        if (!isMarked[i]) {
            dfs(i);
            cc++;
        }
    }

    int q;
    cin >> q;
    for (int i = 0; i < q; ++i) {
        int from, to;
        cin >> from >> to;
        if (d[from] == d[to]) {
            cout << "yes";
        } else {
            cout << "no";
        }
        cout << endl;
    }
    return 0;
}

C++: #include <iostream>
#include <vector>
#include <numeric>
#include <algorithm>
#include <unordered_set>

using namespace std;

const int N_MAX = 100000;
vector<vector<int32_t>> A(N_MAX);
vector<bool> visited(N_MAX);
vector<int32_t> deadend;

void dfs1(int32_t u) {
    visited[u] = true;

    for (int32_t v : A[u]) {
        if (!visited[v]) {
            dfs1(v);
        }
    }

    deadend.push_back(u);

    return;
}

unordered_set<int32_t> dfs2(int32_t u, unordered_set<int32_t> &scc) {
    visited[u] = true;

    for (int32_t v : A[u]) {
        if (!visited[v]) {
            dfs2(v, scc);
        }
    }

    scc.insert(u);

    return scc;
}

int main() {
    fill(visited.begin(), visited.end(), false);

    int32_t n, m;
    cin >> n >> m;

    for (int32_t i = 0; i < m; i++) {
        int32_t s, t;
        cin >> s >> t;

        A[s].push_back(t);
        A[t].push_back(s);
    }

    for (int32_t i = 0; i < n; i++) {
        if (!visited[i]) {
            dfs1(i);
        }
    }

    reverse(deadend.begin(), deadend.end());
    fill(visited.begin(), visited.end(), false);
    vector<unordered_set<int32_t>> sccs;

    for (int32_t u : deadend) {
        if (!visited[u]) {
            unordered_set<int32_t> scc;
            dfs2(u, scc);
            sccs.push_back(scc);
        }
    }

    int32_t q;
    cin >> q;

    for (int32_t i = 0; i < q; i++) {
        int32_t s, t;
        cin >> s >> t;

        bool flag = false;
        for (auto scc : sccs) {
            if (scc.find(s) != scc.end() && scc.find(t) != scc.end()) {
                flag = true;
                break;
            }
        }

        cout << (flag ? "yes" : "no") << endl;
    }

    return 0;
}