Go: package main

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

var scanner = bufio.NewScanner(os.Stdin)

func nextString() string {
	scanner.Scan()
	return scanner.Text()
}

func nextInt() int {
	n, err := strconv.Atoi(nextString())
	if err != nil {
		fmt.Printf("strconv.Atoi failed: %v\n", err)
	}
	return n
}

func newGraph(nNodes int) *Graph {
	g := Graph{}
	g.nodes = make([]*GraphNode, nNodes)
	for iNode := 0; iNode < len(g.nodes); iNode++ {
		g.nodes[iNode] = &GraphNode{}
		g.nodes[iNode].key = GraphNodeKey(iNode)
	}
	return &g
}

var infty = 1000000000

type GraphNodeKey int

// GraphNode is a node for undirected graph
type GraphNode struct {
	key       GraphNodeKey
	adjacents []*GraphNode
	visited   bool
	d, f      int
	parent    *GraphNode
	cc        int
}

func (g *Graph) setAdjacent(l, r GraphNodeKey) {
	g.nodes[l].adjacents = append(g.nodes[l].adjacents, g.nodes[r])
}

// Graph is a undirected graph
type Graph struct {
	nodes []*GraphNode
}

func (g *Graph) initialize() {
	for iNode := 0; iNode < len(g.nodes); iNode++ {
		g.nodes[iNode].visited = false
		g.nodes[iNode].d = infty
		g.nodes[iNode].f = infty
		g.nodes[iNode].parent = nil
		g.nodes[iNode].cc = -1 // 22.3-12
	}
}

type QueueEntry struct {
	node *GraphNode
	next *QueueEntry
}

type Queue struct {
	head, tail *QueueEntry
}

func (q *Queue) enqueue(node *GraphNode) {
	entry := QueueEntry{}
	entry.node = node

	if q.tail == nil {
		q.head = &entry
		q.tail = &entry
		return
	}

	q.tail.next = &entry
	q.tail = q.tail.next
}

func (q *Queue) dequeue() *QueueEntry {
	if q.head == nil {
		return nil
	}
	poped := q.head
	q.head = q.head.next
	if q.head == nil {
		q.tail = nil
	}
	return poped
}

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

var time = 0

func fillDistancesByDepthFirstSearch(g *Graph) {
	g.initialize()
	time = 0
	cc := 0

	for _, u := range g.nodes {
		if !u.visited {
			dfsVisit(g, u, cc)
			cc++
		}
	}
}

func dfsVisit(g *Graph, u *GraphNode, cc int) {
	time++
	u.d = time
	u.cc = cc

	u.visited = true
	for _, v := range u.adjacents {
		if !v.visited {
			v.parent = u
			dfsVisit(g, v, cc)
		}
	}
	time++
	u.f = time
}

func main() {
	scanner.Split(bufio.ScanWords)

	nUsers := nextInt()
	nEdges := nextInt()
	graph := newGraph(nUsers)
	for iEdge := 0; iEdge < nEdges; iEdge++ {
		l := GraphNodeKey(nextInt())
		r := GraphNodeKey(nextInt())
		graph.setAdjacent(l, r)
		graph.setAdjacent(r, l)
	}

	fillDistancesByDepthFirstSearch(graph)

	nQueries := nextInt()
	for iQuery := 0; iQuery < nQueries; iQuery++ {
		l := GraphNodeKey(nextInt())
		r := GraphNodeKey(nextInt())

		// fmt.Println(graph.nodes[l].d, graph.nodes[r].d, graph.nodes[r].f, graph.nodes[l].f)
		if graph.nodes[l].cc == graph.nodes[r].cc {
			fmt.Println("yes")
		} else {
			fmt.Println("no")
		}
	}
}

C++: #include <iostream>
#include <vector>
#include <cstdio>
using namespace std;
int n,m;
vector <int> rel[100000];
int id[100001];
int visit[100001] = {0};
int s,t;


void check(int x, int u) { 
 visit[x] = 1;
  id[x] = u;

  int v ;
  for(int i=0;i<rel[x].size();i++) {
    v = rel[x][i];
    if(visit[v] == 0) {
      check(v,u);
    }
  }
}
    
  

int main() {

 

  cin >> n >> m;

 
  int a,b;


  for(int i=0;i<m;i++) {


    cin >> a >> b;

    rel[a].push_back(b);
    rel[b].push_back(a);

  }
  
  for(int i =0;i<n;i++) {
    if(visit[i] == 0) {
      check(i,i);
    }
  }
  

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

  return 0;

}

C++: #include<bits/stdc++.h>
using namespace std;

int n,m,q;
int s,t;
int ck[100002];
list<int>l[100002];
list<int>ans[100002];
queue<int>que;

int slv(int x);

int main(){
  cin>>n>>m;
  for(int i=0;i<n;i++)ck[i]=0;
  for(int i=0;i<m;i++){
    cin>>s>>t;
    l[s].push_back(t);
    l[t].push_back(s);
  }

  for(int i=0;i<n;i++){
    if(ck[i]==0){
      while(!que.empty())que.pop();
      que.push(i);
      slv(i);
    }
  }

  cin>>q;
  for(int i=0;i<q;i++){
    cin>>s>>t;
    int flag=0;
    for(int j=0;j<ans[s].size();j++){
      int x=ans[s].front();
      ans[s].pop_front();
      ans[s].push_back(x);
      if(x==t){
	flag=1;
	break;
      }
    }
    if(flag==1)cout<<"yes"<<endl;
    else cout<<"no"<<endl;
  }

}

int slv(int x){
  for(int i=0;i<l[x].size();i++){
    int y=l[x].front();
    l[x].pop_front();
    l[x].push_back(y);

    for(int j=0;j<que.size();j++){
      int z=que.front();
      que.pop();
      que.push(z);
      ans[z].push_back(y);
      ans[y].push_back(z);
    }

    if(ck[y]==0){
      que.push(y);
      ck[y]=1;
      slv(y);
    }
  }
  return(0);
}

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

using namespace std;

class UnionFindTree {
private:
    vector<int32_t> parent, rank;

    int32_t find(int32_t x) {
        if (parent[x] == x) {
            return x;
        } else {
            int32_t p = find(parent[x]);
            parent[x] = p;
            return p;
        }
    }

public:
    UnionFindTree(int32_t n) {
        parent.resize(n);
        rank.resize(n);

        for (int32_t i = 0; i < n; i++) {
            parent[i] = i;
            rank[i] = 0;
        }
    }

    void unite(int32_t x, int32_t y) {
        x = find(x);
        y = find(y);

        if (x == y) return;

        if (rank[x] < rank[y]) {
            parent[x] = y;
        } else {
            parent[y] = x;
            if (rank[x] == rank[y]) rank[x]++;
        }
    }

    bool same(int32_t x, int32_t y) {
        return find(x) == find(y);
    }
};

int main() {
    int32_t n, m;
    cin >> n >> m;

    UnionFindTree uf(n);

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

        uf.unite(s, t);
    }

    int32_t q;
    cin >> q;

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

        cout << (uf.same(s, t) ? "yes" : "no") << endl;
    }

    return 0;
}

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

int n, m, s, t, u;
vector<vector <int> > a;
bool f[100000];

bool path(int s1) {
	f[s1] = 1;
	for (int i = 0; i < (int) a[s1].size(); i++) {
		if (a[s1][i] == t) {
			return true;
		}
		else if (!f[a[s1][i]])
			if (path(a[s1][i]))
				return true;
	}
	return false;
}

int main()
{
	cin >> n >> m;

	a.resize(n);

	for (int i = 0; i < m; i++) {
		int u, v;
		cin >> u >> v;
		a[u].push_back(v);
		a[v].push_back(u);
	}

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

	for (int i = 0; i < n; i++)
		f[i] = 0;

		if(path(s))
			cout << "yes" << endl;
		else
			cout << "no" << endl;
	}

	return 0;
}

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

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 assignColor() {
  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);
  }

  assignColor();

  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;
}